General Computing & Hardware:

• AI: Artificial Intelligence
• BIOS: Basic Input/Output System
• CPU: Central Processing Unit
• GPU: Graphics Processing Unit
• HDD: Hard Disk Drive
• HDMI: High-Definition Multimedia Interface
• LED: Light Emitting Diode
• LCD: Liquid Crystal Display
• OS: Operating System
• RAM: Random Access Memory
• ROM: Read-Only Memory
• SSD: Solid State Drive
• USB: Universal Serial Bus
• Wi-Fi: Wireless Fidelity (though often just "Wireless LAN")

Networking & Internet:

• API: Application Programming Interface
• CDN: Content Delivery Network
• DHCP: Dynamic Host Configuration Protocol
• DNS: Domain Name System
• FTP: File Transfer Protocol
• HTTP: HyperText Transfer Protocol
• HTTPS: HyperText Transfer Protocol Secure
• IP: Internet Protocol
• ISP: Internet Service Provider
• LAN: Local Area Network
• MAC: Media Access Control
• P2P: Peer-to-Peer
• TCP: Transmission Control Protocol
• URL: Uniform Resource Locator
• VPN: Virtual Private Network
• WAN: Wide Area Network
• WWW: World Wide Web

Software & Development:

• CLI: Command Line Interface
• CSS: Cascading Style Sheets
• GUI: Graphical User Interface
• HTML: HyperText Markup Language
• IDE: Integrated Development Environment
• JPEG/JPG: Joint Photographic Experts Group
• PDF: Portable Document Format
• SQL: Structured Query Language
• XML: eXtensible Markup Language

Cloud Computing & Services:

• IaaS: Infrastructure as a Service
• PaaS: Platform as a Service
• SaaS: Software as a Service

Cybersecurity:

• 2FA: Two-Factor Authentication
• ACL: Access Control List
• DLP: Data Loss Prevention
• IDS: Intrusion Detection System
• IPS: Intrusion Prevention System
• MFA: Multi-Factor Authentication
• SIEM: Security Information and Event Management
• SSL: Secure Sockets Layer
• TLS: Transport Layer Security
• VPN: Virtual Private Network (also in Networking)

Telecommunications:

• ADSL: Asymmetric Digital Subscriber Line
• ATM: Asynchronous Transfer Mode
• GSM: Global System for Mobile Communications
• LTE: Long Term Evolution
• VoIP: Voice over Internet Protocol

Other Important Acronyms:

• IoT: Internet of Things
• IT: Information Technology
• OEM: Original Equipment Manufacturer
• R&D: Research and Development
• QA: Quality Assurance
• UPS: Uninterruptible Power Supply