HTTP / HTTPS
Hypertext Transfer Protocol – the communication protocol of the web. HTTPS is the encrypted variant with TLS/SSL and the standard for all sites.
HTTP is the protocol that makes the web work. Every time you open a site, call an API or submit a form, the browser and server use HTTP. HTTPS adds encryption and is no longer optional: browsers mark HTTP as insecure and Google favours HTTPS in ranking.
What is HTTP / HTTPS?
HTTP (Hypertext Transfer Protocol) is an application-layer protocol for transferring hypermedia (HTML, JSON, images) between client (browser) and server. HTTP is stateless: each request is independent; the server doesn’t remember previous ones (sessions use cookies or tokens). HTTPS (HTTP Secure) is the encrypted variant: TLS (Transport Layer Security, successor to SSL) encrypts all traffic. A TLS certificate (e.g. from Let’s Encrypt) proves the server’s identity. HTTP/2 and HTTP/3 (with QUIC) add multiplexing, header compression and UDP-based transport.
How does HTTP / HTTPS work?
HTTP flow: 1) DNS: browser resolves the hostname to an IP. 2) TCP (or QUIC for HTTP/3): connection is established. 3) TLS handshake (HTTPS): exchange certificates and keys, establish encrypted channel. 4) HTTP request: client sends method (GET, POST, PUT, DELETE), URL, headers and optional body. 5) Server processes and builds response. 6) HTTP response: status code (200 OK, 301 Redirect, 404 Not Found, 500 Server Error), headers and body. HTTP/2 allows multiple requests over one connection (multiplexing).
Practical Examples
GET request: Browser requests GET /products?category=software – server responds with a JSON list.
POST request: A form sends POST /api/contact with name, email and message – server processes and returns e.g. 201 Created.
301 redirect: An old URL permanently redirects to the new one – search engines transfer ranking.
CORS: A frontend on app.example.com calls api.example.com – CORS headers allow the cross-origin request.
Typical Use Cases
Web browsing: Loading pages, images, videos and documents
REST APIs: Communication between frontend and backend via HTTP methods
Webhooks: Server-to-server notifications via HTTP POST on events
File downloads: Transfer with resume (Range header)
Streaming: HLS and DASH for video
Advantages and Disadvantages
Advantages
- Universal: HTTP works everywhere – browsers, apps, IoT, CLI
- HTTPS encryption protects data from eavesdropping and tampering
- HTTP/2 and HTTP/3 improve performance over HTTP/1.1
- Let’s Encrypt provides free TLS certificates
- Caching: Cache-Control, ETag reduce latency and server load
Disadvantages
- Stateless: Sessions and auth need cookies, tokens or similar
- Overhead: Headers and TLS handshake add latency, especially with many small requests
- Mixed content: Browsers block HTTP resources on HTTPS pages
- Certificates: Expired or wrong certs cause errors and warnings
Frequently Asked Questions about HTTP / HTTPS
Is HTTPS really necessary?
What’s the difference between HTTP/1.1, HTTP/2 and HTTP/3?
How do I set up HTTPS?
Related Terms
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