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AES-256Advanced Encryption Standard with 256-bit keys. The gold standard for symmetric encryption used by most VPNs. Considered unbreakable with current technology.D
DNSDomain Name System. Translates domain names (google.com) to IP addresses (142.250.80.46). DNS queries reveal which sites you visit. A VPN encrypts DNS queries.DNS LeakWhen DNS queries bypass the VPN tunnel and go directly to your ISP's DNS servers, revealing which sites you visit despite being connected to a VPN. E
End-to-End Encryption (E2EE)Encryption where only the sender and recipient can read the data. Not even the service provider can decrypt it. Used by Signal, WhatsApp messages, and ProtonMail.F
Five EyesIntelligence alliance between US, UK, Canada, Australia, and New Zealand. Member countries share signals intelligence. VPN providers based outside Five Eyes can't be compelled to share data with these governments.G
GDPRGeneral Data Protection Regulation. EU law governing data protection and privacy. Gives EU residents rights over their personal data including the right to erasure.Great Firewall (GFW)China's internet censorship system that blocks access to thousands of websites and services including Google, Facebook, and Twitter. Uses deep packet inspection to detect and block VPN traffic. I
IKEv2Internet Key Exchange version 2. A VPN protocol known for fast reconnection when switching between Wi-Fi and cellular networks, making it popular on mobile devices.IP AddressInternet Protocol address. A unique number assigned to your device on a network. A VPN replaces your real IP with the VPN server's IP, hiding your location. ISPInternet Service Provider. The company providing your internet connection (e.g., Comcast, BT, Telstra). Your ISP can see your browsing activity without a VPN. K
Kill SwitchA VPN feature that blocks all internet traffic if the VPN connection drops. Prevents accidental data exposure. Essential for security-critical work.M
Man-in-the-Middle (MITM)An attack where someone intercepts communication between two parties. Common on public Wi-Fi. A VPN prevents MITM attacks by encrypting all traffic.N
No-Logs PolicyA VPN provider's commitment to not record user activity, connection timestamps, IP addresses, or browsing data. Should be verified by independent audits.O
ObfuscationTechnology that disguises VPN traffic as regular HTTPS traffic. Used to bypass VPN blocking in countries like China and on restrictive networks.OpenVPNAn open-source VPN protocol with a 20+ year track record. Supports both UDP (faster) and TCP (more reliable) modes. The most widely supported protocol. P
PasskeyA passwordless authentication method using public-key cryptography. Stored on your device and verified biometrically. More secure than passwords + 2FA.PhishingA social engineering attack where an attacker impersonates a trusted entity to trick you into revealing passwords, credit card numbers, or other sensitive data. ProtocolIn VPN context, the set of rules determining how data is encrypted and transmitted. Common protocols: WireGuard, OpenVPN, IKEv2. Each offers different speed/security trade-offs. R
RAM-Only ServersVPN servers that run entirely in RAM with no hard drives. All data is wiped on reboot. Used by NordVPN, ExpressVPN, and Surfshark for enhanced privacy.S
Split TunnelingA VPN feature that routes only selected traffic through the VPN while sending the rest directly. Useful for routing work apps through VPN while allowing personal apps to connect directly.T
TLS/SSLTransport Layer Security / Secure Sockets Layer. The encryption behind HTTPS (the padlock icon in your browser). Encrypts data between your browser and the website.Two-Factor Authentication (2FA)A security method requiring two forms of verification: something you know (password) and something you have (authenticator app code or hardware key). V
VPNVirtual Private Network. Creates an encrypted tunnel between your device and a VPN server, hiding your IP address and encrypting all internet traffic from your ISP and local network.W
WebRTC LeakA browser vulnerability that can reveal your real IP address even when using a VPN. Caused by WebRTC (used for video calls). Can be mitigated by VPN apps or browser extensions.WireGuardA modern VPN protocol with minimal code (~4,000 lines vs OpenVPN's 70,000+). Uses state-of-the-art cryptography. The fastest open-source VPN protocol available in 2026. Z
Zero-Knowledge EncryptionEncryption where the service provider cannot access your data, even if compelled. Your encryption key never leaves your device. Used by password managers and some cloud storage providers.