What Is the A+? Glossary & Key Terms

BIOS
Basic Input/Output System — legacy firmware stored on a motherboard chip that initializes hardware and starts the boot process before an OS loads.
UEFI
Unified Extensible Firmware Interface — the modern replacement for BIOS, offering faster boot, GPT support, a graphical setup interface, and Secure Boot.
POST
Power-On Self-Test — a firmware-run diagnostic that checks essential hardware at startup and reports failures via beep codes or on-screen errors.
CMOS
Complementary Metal-Oxide-Semiconductor — the battery-backed memory chip that stores firmware settings such as boot order and system time between power cycles.
NIC
Network Interface Card — the hardware component that connects a device to a wired or wireless network.
DHCP
Dynamic Host Configuration Protocol — a service that automatically assigns IP addresses and network configuration to devices on a network.
DNS
Domain Name System — the service that resolves human-readable domain names into IP addresses.
NAT
Network Address Translation — a technique that maps multiple private IP addresses to one or more public IP addresses at a network boundary.
VLAN
Virtual Local Area Network — a logical grouping of devices on a switch that separates broadcast traffic without requiring separate physical hardware.
VPN
Virtual Private Network — an encrypted tunnel that extends a private network across a public network, allowing secure remote access.
RAID
Redundant Array of Independent Disks — a method of combining multiple physical drives into a logical unit for performance, redundancy, or both, depending on the RAID level used.
SSD
Solid State Drive — a storage device using flash memory with no moving parts, offering faster read/write speeds and better durability than traditional hard drives.
NVMe
Non-Volatile Memory Express — a high-speed storage protocol designed for SSDs connected via PCIe, offering much lower latency than SATA-based storage.
Hypervisor
Software that creates and manages virtual machines by allocating a physical host's hardware resources among one or more guest operating systems.
IaaS
Infrastructure as a Service — a cloud model providing virtualized computing resources like servers, storage, and networking on demand.
PaaS
Platform as a Service — a cloud model providing a managed environment for developing, testing, and deploying applications without managing underlying infrastructure.
SaaS
Software as a Service — a cloud model delivering fully functional software applications to users over the internet, typically via subscription.
ACL
Access Control List — a set of rules that permits or denies specific traffic, users, or actions on a network device, file, or system resource.
MFA
Multifactor Authentication — a security method requiring two or more independent verification factors to confirm a user's identity.
Malware
Malicious software designed to damage, disrupt, or gain unauthorized access to a computer system, encompassing viruses, worms, trojans, ransomware, and spyware.
Phishing
A social engineering attack that uses deceptive emails or messages impersonating a trusted source to trick victims into revealing sensitive information or credentials.
Ransomware
Malware that encrypts a victim's files or locks system access, demanding payment in exchange for restoring access.
UPS
Uninterruptible Power Supply — a battery-backed device that provides temporary power during an outage to protect equipment and allow safe shutdown.
Change Management
A formal, documented process for requesting, evaluating, approving, and implementing changes to IT systems in a controlled and auditable manner.
Least Privilege
A security principle stating that users and processes should be granted only the minimum access rights necessary to perform their required functions.