CompTIA A+ Certification Exam Core 1 Glossary

Definitions and pro-tips for the 220-1101 certification.

C

Cloud Computing

Cloud computing delivers on-demand access to computing resources—servers, storage, databases, networking, software, and analytics—over the internet. This model shifts IT infrastructure from on-premises ownership to a pay-as-you-go service, offering scalability and flexibility.

CMOS Battery

The CMOS battery is a small, coin-cell battery on the motherboard providing power to the CMOS chip. This chip retains the system’s BIOS settings, including boot order, date, and time, even when the computer is powered off, ensuring proper system startup.

Command Line Interface (CLI)

A Command Line Interface is a text-based method for interacting with a computer’s operating system. Users type commands to execute tasks, offering precise control and automation capabilities. CLIs are essential for system administration, scripting, and advanced troubleshooting, bypassing graphical user interface limitations.

Command Prompt

The Command Prompt is a text-based interface for interacting with the Windows operating system. Users enter commands to perform tasks, manage files, configure system settings, and troubleshoot issues, providing a powerful alternative to the graphical user interface.

CPU

The central processing unit (CPU) is the primary component executing instructions within a computer. It fetches, decodes, and executes program instructions, performing arithmetic, logical, control, and input/output operations. CPU performance is influenced by clock speed, core count, and cache size.

D

DDR4 (Double Data Rate 4) SDRAM

DDR4 (Double Data Rate 4) SDRAM is a type of synchronous dynamic random-access memory used in modern computers to store temporary data. It offers higher speeds and lower power consumption compared to DDR3, utilizing a 288-pin configuration for standard desktop memory modules.

Digitizer

A digitizer is a hardware component that converts analog touch or pen input into a digital signal that the device can process. It is the glass layer sitting atop a screen that enables touch-screen functionality in smartphones and tablets.

DisplayPort

DisplayPort is a digital display interface designed primarily for connecting a video source, such as a computer, to a display device. It supports higher resolutions and refresh rates than older standards and is commonly found on high-end graphics cards and monitors, offering features like daisy-chaining.

DNS (Domain Name System)

DNS is a hierarchical and distributed naming system that translates human-readable domain names into numerical IP addresses. This translation process enables users to access online resources without memorizing complex IP addresses, forming the foundation of internet navigation.

Driver

A driver is software facilitating communication between the operating system and a hardware device. It translates OS commands into a format the device understands, and vice versa. Proper driver installation is crucial for device functionality and system stability. Incorrect drivers can cause conflicts or failures.

Dynamic Host Configuration Protocol (DHCP)

Dynamic Host Configuration Protocol (DHCP) is a network management protocol used to automatically assign IP addresses and other communication parameters to devices. It eliminates the need for manual configuration by leasing addresses from a central server to clients on a network.

Dynamic IP Address

A Dynamic IP Address is a temporary numerical label automatically assigned to a network device by a Dynamic Host Configuration Protocol (DHCP) server. These addresses are leased for a specific duration and can change upon lease renewal, simplifying network administration.

E

ECC (Error Correction Code) RAM

ECC RAM is a specialized type of computer memory that can detect and fix the most common kinds of internal data corruption. It is primarily used in servers and workstations to prevent system crashes caused by single-bit memory errors.

eMMC

eMMC (embedded MultiMediaCard) is a flash storage solution commonly found in budget-friendly devices like smartphones, tablets, and Chromebooks. It integrates flash memory and a memory controller into a single chip, providing a compact and cost-effective storage option.

Encryption

Encryption is a data security process transforming readable data (plaintext) into an unreadable format (ciphertext) using an algorithm and a key. This protects confidentiality during storage and transmission. Decryption reverses the process, requiring the correct key to restore the original data.

ESD

Electrostatic Discharge is the rapid transfer of electrical charge between objects with differing static electricity potentials. This can damage sensitive electronic components, even with voltages below what humans can feel, causing immediate failure or latent defects.

ESD Safe Packaging

ESD Safe Packaging utilizes materials designed to prevent damage to sensitive electronic components caused by electrostatic discharge (ESD). These materials dissipate static electricity, protecting components from potentially destructive voltage spikes during handling and storage.

Expansion Slot

An expansion slot is a socket on the motherboard that allows for the addition of expansion cards, enhancing a computer’s capabilities. These slots provide connectivity for components like graphics cards, sound cards, and network adapters, extending the system’s functionality.

I

IMAP (Internet Message Access Protocol)

IMAP is an email retrieval protocol that allows clients to access messages stored on a mail server. Unlike POP3, IMAP synchronizes the mail across multiple devices, ensuring that changes made on one device are reflected everywhere.

Impact Printer

An impact printer is a type of printer that produces images by physically striking an inked ribbon against paper. Common examples include dot-matrix printers, which are still used today for creating multi-part carbon copy forms.

Infrastructure as a Service (IaaS)

Infrastructure as a Service (IaaS) is a cloud computing model that provides virtualized computing resources, such as servers, storage, and networking, over the internet. Users are responsible for managing the operating system, middleware, and applications installed on the infrastructure.

Inkjet Printer

Inkjet printer is a type of computer printer that creates images by spraying tiny droplets of liquid ink onto paper. It is commonly used for high-quality photo printing and home office documents due to its ability to blend colors effectively.

Internet Protocol version 6 (IPv6)

Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol, designed to replace IPv4. It uses 128-bit addresses, providing a significantly larger address space to accommodate the growing number of devices connected to the global internet.

IP Address

An Internet Protocol (IP) address is a numerical label assigned to each device connected to a computer network utilizing the Internet Protocol. It enables logical identification and location addressing for communication between devices across networks, facilitating data transmission.

IPS (In-Plane Switching)

IPS is a type of LCD panel technology that aligns liquid crystals in a plane parallel to the glass. This design provides superior color reproduction and much wider viewing angles compared to TN (Twisted Nematic) panels.

IPv4 (Internet Protocol version 4)

IPv4 is the fourth version of the Internet Protocol, utilizing a 32-bit addressing scheme to identify devices on a network. It is the most widely used IP version, though it is limited by a finite number of available addresses.

P

Peripheral Device

A peripheral device connects to a computer system to provide input, output, or auxiliary functions. These external devices expand the computer’s capabilities beyond its core processing functions. Examples include keyboards, mice, printers, storage devices, and cameras.

PGA (Pin Grid Array)

PGA (Pin Grid Array) is a CPU socket design where the pins are located on the bottom of the processor and fit into holes in the motherboard socket. This architecture is traditionally associated with AMD processors and requires careful handling during installation.

Phishing

Phishing is a social engineering technique where attackers deceive individuals into revealing sensitive information—usernames, passwords, credit card details—through fraudulent communications. These communications often mimic legitimate organizations and exploit trust to compromise security.

Platform as a Service (PaaS)

Platform as a Service (PaaS) is a cloud computing model that provides a framework for developers to build, test, and deploy applications. It includes the underlying infrastructure, operating systems, and development tools, allowing users to focus solely on coding.

PoE

Power over Ethernet (PoE) is a technology that delivers electrical power through standard Ethernet cables alongside data. This allows devices like IP cameras, VoIP phones, and wireless access points to receive both power and data connectivity from a single cable.

POP3 (Post Office Protocol version 3)

POP3 is a protocol used by email clients to retrieve messages from a mail server. By default, it downloads the emails to the local device and deletes them from the server, making it unsuitable for multi-device access.

POST

Power-On Self-Test is the initial diagnostic sequence executed by a computer’s BIOS or UEFI firmware upon startup. It verifies essential hardware components like CPU, memory, and storage before loading the operating system, reporting errors if failures are detected.

Power Supply Unit (PSU)

The Power Supply Unit (PSU) converts AC power from the wall outlet into DC power usable by computer components. Wattage indicates the total power output, while efficiency ratings (80+ Bronze, Gold, Platinum) reflect energy conservation. Modular PSUs allow for selective cable connections.

R

RAID 0 (Redundant Array of Independent Disks 0)

RAID 0 (Redundant Array of Independent Disks 0), also known as striping, distributes data across two or more disks to increase read and write performance. It provides no redundancy, meaning the failure of a single drive results in total data loss.

RAID 1 (Redundant Array of Independent Disks 1)

RAID 1 (Redundant Array of Independent Disks 1), known as mirroring, duplicates data across two or more disks. This provides high data redundancy, ensuring that if one drive fails, the system remains operational using the mirrored copy.

RAID 10 (Redundant Array of Independent Disks 10)

RAID 10 (Redundant Array of Independent Disks 10) combines the mirroring of RAID 1 and the striping of RAID 0. It provides the high performance of striping and the high redundancy of mirroring, requiring a minimum of four disks.

RAID 5 (Redundant Array of Independent Disks 5)

RAID 5 (Redundant Array of Independent Disks 5) uses block-level striping with distributed parity across three or more disks. This configuration balances performance and redundancy, allowing the array to survive the failure of a single drive without data loss.

RAM

Random Access Memory (RAM) is volatile memory used for actively processing data. It allows rapid read and write access to any location, enabling quick application loading and multitasking. Capacity and speed (measured in MHz) significantly impact system performance.

RDP (Remote Desktop Protocol)

RDP is a proprietary protocol developed by Microsoft that allows a user to remotely connect to and control another computer over a network. It provides a full graphical interface of the remote machine to the client device.

Remote Desktop Protocol (RDP)

Remote Desktop Protocol (RDP) is a proprietary protocol developed by Microsoft that provides a user with a graphical interface to connect to another computer over a network. It allows for full remote control of the target system's desktop environment.

RFID

Radio-Frequency Identification (RFID) employs electromagnetic fields to automatically identify and track tags attached to objects. These tags contain electronically stored information, allowing for non-contact reading and identification in various applications, including inventory management and supply chain tracking.

RJ-11

RJ-11 is a standardized physical interface used primarily for telephone connections and legacy modem connections. It utilizes a six or four-position, two-conductor modular connector. While resembling RJ-45, it is incompatible and transmits analog signals, not digital Ethernet data.

RJ-45

RJ-45 is a standardized 8-pin/8-position modular connector commonly used for Ethernet network connections. It facilitates data transmission over twisted-pair cabling, enabling devices to connect to local area networks (LANs) and the internet. Proper crimping is essential for reliable connectivity.

Router

A router is a networking device that forwards data packets between computer networks. Operating at Layer 3 (Network Layer) of the OSI model, it uses IP addresses to determine the best path for data transmission, enabling communication between different networks, including LANs and the WAN.

S

S.M.A.R.T.

Self-Monitoring, Analysis and Reporting Technology is a system built into hard drives and SSDs that monitors drive health and predicts potential failures. It tracks attributes like read error rate and spin-up time, providing early warnings of impending issues to allow for data backup and drive replacement.

SaaS (Software as a Service)

Software as a Service (SaaS) is a cloud computing model where applications are hosted by a provider and made available to users over the internet. Users typically pay a subscription fee to access the software via a web browser without installing it locally.

SATA (Serial Advanced Technology Attachment)

Serial Advanced Technology Attachment (SATA) is a computer bus interface used to connect host bus adapters to mass storage devices like HDDs and SSDs. It replaced the older PATA standard, offering faster data transfer speeds and thinner cables for better airflow.

Secure Shell (SSH)

Secure Shell (SSH) is a cryptographic network protocol used for operating network services securely over an unsecured network. It is most commonly used for remote command-line login and remote command execution, providing strong encryption for the session.

Serial Port

A Serial Port is a communication interface used to transmit data one bit at a time. Historically used for connecting peripherals like modems and mice, it’s now often found in specialized equipment and legacy systems, identified by designations like COM1 or COM2.

SIM Card (Subscriber Identity Module)

A subscriber identity module (SIM) card is a removable smart card used in mobile devices to store the international mobile subscriber identity (IMSI) number. It identifies the user to the network provider and allows the device to connect to cellular services.

SMTP (Simple Mail Transfer Protocol)

SMTP is the standard communication protocol used for sending email messages from a client to a server or between servers. It operates primarily on port 25 or 587 to push mail toward its final destination.

SO-DIMM (Small Outline Dual In-line Memory Module)

SO-DIMM (Small Outline Dual In-line Memory Module) is a smaller form factor of RAM designed specifically for laptops, small form factor PCs, and printers. It provides the same functionality as standard DIMMs but occupies significantly less physical space on the system motherboard.

Software as a Service (SaaS)

Software as a Service (SaaS) is a cloud computing model where applications are hosted by a provider and delivered to users over the internet. Users typically access the software via a web browser, eliminating the need for local installation and maintenance.

SOHO Network

A Small Office/Home Office (SOHO) network is a typical network setup for small businesses and residential use. These networks commonly utilize all-in-one devices like routers that integrate switching, routing, and wireless access point functionalities into a single unit.

Solid State Drive (SSD)

A Solid State Drive (SSD) is a data storage device utilizing flash memory to store persistent data. SSDs offer significantly faster read/write speeds, lower latency, and increased durability compared to traditional Hard Disk Drives (HDDs) due to the absence of moving mechanical parts.

SSD

A Solid State Drive (SSD) is a storage device utilizing flash memory to persistently store data. Offering faster access times and increased durability compared to HDDs, SSDs improve system responsiveness and boot times. NVMe SSDs provide significantly higher speeds than SATA SSDs.

SSH (Secure Shell)

Secure Shell (SSH) is a cryptographic network protocol used for operating network services securely over an unsecured network. It provides a secure channel for remote command-line login and other secure network services, replacing the insecure Telnet protocol.

SSID (Service Set Identifier)

SSID (Service Set Identifier) is the unique name assigned to a wireless local area network (WLAN) to distinguish it from other nearby networks. It allows client devices to identify and connect to the correct wireless access point among multiple available signals.

Static Electricity

Static electricity is the result of an imbalance of electrical charges on a surface. This buildup can discharge unexpectedly, generating electromagnetic interference capable of damaging delicate electronic components. Proper grounding and anti-static measures are crucial during computer repair.

Static IP Address

A Static IP Address is a permanently assigned numerical label to a network device, manually configured and remaining constant unless changed. This contrasts with dynamic addresses, providing consistent network access for servers, printers, and other critical infrastructure.

Switch

A network switch is a Layer 2 device that forwards data packets between devices on a network. Utilizing MAC addresses, it learns and maintains a forwarding table to efficiently direct traffic only to the intended recipient, improving network performance and security compared to hubs.

T

TCP (Transmission Control Protocol)

Transmission Control Protocol (TCP) is a connection-oriented communication protocol that ensures reliable delivery of data packets across a network. It uses a three-way handshake to establish a connection and tracks packets to guarantee they arrive in the correct order.

TFT (Thin Film Transistor)

Thin Film Transistor (TFT) is an active-matrix version of a liquid crystal display (LCD) that improves image quality and response time. It uses a separate transistor for each pixel, allowing for better control of light and sharper colors.

Thermal Paste

Thermal paste, also known as thermal grease, is a thermally conductive compound applied between a heat source (like a CPU) and a heatsink. It fills microscopic gaps, improving heat transfer efficiency by eliminating air pockets, which are poor conductors of heat.

Thermal Printer

Thermal printer is a device that produces images by applying heat to specialized heat-sensitive paper. This technology eliminates the need for ink or toner cartridges, making it the ideal choice for printing receipts and shipping labels in commercial environments.

Thunderbolt

Thunderbolt is a high-speed hardware interface co-developed by Intel and Apple, enabling the connection of external devices. Utilizing a USB-C connector in recent iterations, it combines PCI Express and DisplayPort protocols for data, video, and power delivery, offering significantly faster transfer rates.

TPM (Trusted Platform Module)

TPM is a specialized chip on a motherboard that provides hardware-based security functions, such as generating and storing cryptographic keys. It is essential for enabling full-disk encryption like Windows BitLocker to protect sensitive data from unauthorized access.

Transmission Control Protocol (TCP)

Transmission Control Protocol (TCP) is a connection-oriented transport layer protocol that ensures reliable delivery of data packets. It uses a three-way handshake to establish a connection and verifies that all data is received correctly and in order.

Troubleshooting Methodology

Troubleshooting methodology is a systematic, logical process for identifying and resolving technical issues. It involves defining the problem, creating a hypothesis, testing the hypothesis, implementing a solution, and verifying the resolution. A structured approach minimizes wasted time and ensures effective problem-solving.

U

UDP (User Datagram Protocol)

User Datagram Protocol (UDP) is a connectionless communication protocol used for fast, low-latency data transmission where perfect reliability is not required. It sends packets without establishing a connection or verifying receipt, making it ideal for streaming and gaming.

UEFI

Unified Extensible Firmware Interface is a modern firmware interface replacing BIOS. It initializes hardware and loads the operating system. UEFI supports Secure Boot, larger hard drives exceeding 2TB, and faster boot times through improved initialization processes and standardized drivers.

Uninterruptible Power Supply (UPS)

Uninterruptible Power Supply (UPS) is a device that provides emergency power to a computer system when the main power source fails. It uses batteries to prevent sudden shutdowns, allowing users to save work and shut down the system safely.

UPS

Uninterruptible Power Supply provides temporary power when the primary power source is lost. It protects hardware from damage and prevents data loss by allowing a safe shutdown. UPS units vary in capacity and topology, impacting their suitability for different workloads.

USB

Universal Serial Bus is an industry standard for connecting devices to a computer. It defines cables, connectors, and communication protocols for data transfer and power delivery. USB standards have evolved, increasing data transfer speeds and power output capabilities over time, impacting peripheral compatibility.

User Datagram Protocol (UDP)

User Datagram Protocol (UDP) is a connectionless transport layer protocol that sends data packets without establishing a formal connection or verifying receipt. This reduces overhead and latency, making it ideal for time-sensitive applications like streaming and gaming.

V

VDI (Virtual Desktop Infrastructure)

Virtual Desktop Infrastructure (VDI) is a technology that hosts a desktop operating system on a centralized server in a data center. Users access their personalized virtual desktop remotely from any device, ensuring consistent environments and centralized management.

VGA

Video Graphics Array (VGA) is an analog video display standard. It transmits video signals using a 15-pin D-sub connector. While largely superseded by digital standards like HDMI and DisplayPort, VGA remains relevant for compatibility with older hardware and troubleshooting legacy systems.

Virtual Machine (VM)

A virtual machine is a software-based emulation of a physical computer that runs its own operating system and applications independently. It operates in an isolated environment, allowing users to run multiple different OSs on a single physical piece of hardware.

Virtual Private Network (VPN)

A Virtual Private Network establishes a secure, encrypted connection over a less secure network, typically the internet. It creates a private network tunnel, protecting data confidentiality and integrity. VPNs mask the user’s IP address, providing enhanced privacy and secure remote access to resources.

Virtualization

Virtualization creates software-based versions of physical resources like servers, operating systems, or storage devices. This allows multiple operating systems to run concurrently on a single physical machine, improving resource utilization and reducing hardware costs. It’s a core component of modern IT infrastructure.

VLAN (Virtual Local Area Network)

VLAN (Virtual Local Area Network) is a logical grouping of devices on one or more physical LANs that allows network administrators to segment traffic. This improves security and reduces broadcast traffic by isolating groups of users regardless of their physical location.

VoIP (Voice over IP)

VoIP (Voice over IP) is a technology that allows voice calls to be made using a broadband internet connection instead of a traditional analog phone line. It converts analog audio signals into digital data packets for transmission over IP networks.

VPN (Virtual Private Network)

A VPN establishes an encrypted tunnel over a public network, enabling secure remote access to resources and protecting data confidentiality. It masks the user’s IP address, providing privacy and bypassing geographical restrictions by routing internet traffic through a remote server.

VRM

Voltage Regulator Module is a circuit that provides stable voltage to the CPU and other components. It converts the power supply’s DC voltage into the lower, precise voltages required by the processor, ensuring consistent and reliable operation.