Glossary: technology

Terms that appear on this site's error, security and character pages.

HTTP status code: A 3-digit number the server sends with its response, saying whether it worked (2xx), was redirected (3xx), was a visitor-side error (4xx) or a server-side error (5xx).
Gateway: An intermediate server between the visitor and the final server (reverse proxy, load balancer, CDN). "Bad gateway" errors happen when that intermediary gets no valid response.
DNS: The system that translates an address like "example.com" into the server's IP number. When DNS fails, the browser has nowhere to send the request.
SSL/TLS certificate: A file that proves a site's identity and enables the encrypted connection (the browser lock icon). Expired or misconfigured, it causes an insecure-connection error.
Browser cache: A local copy of pages and files the browser keeps to load faster next time. Stale cache sometimes causes errors a hard refresh fixes.
Data breach: An event where account information (emails, passwords) from a service is exposed or stolen and ends up circulating publicly.
Phishing: A fake message or site that imitates a real company to steal a password, card details or other personal data.
Two-factor authentication: Requiring, besides the password, a second proof of identity (phone code, physical key) to sign in to an account.
Unicode code point: The unique number the Unicode standard assigns to every character or emoji, written as U+ followed by hex digits.
Emoji: A Unicode character with its own picture (face, object, flag), whose look varies by app and system but whose code stays fixed.