http-protocol

Without a standardized protocol, every client and server would need custom communication logic. Each request would need to define how to format data, indicate success/failure, handle errors. HTTP provides this shared language so any client can talk to any server.

HTTP (Hypertext Transfer Protocol) is a text-based request-response protocol that defines how clients and servers exchange messages. It operates over TCP (or TLS for HTTPS), with a simple structure: method, path, headers, optional body. The server processes the request and returns a status code, headers, and body.

1. Request Line: Client sends “GET /users HTTP/1.1” specifying method, path, protocol version
2. Headers: Additional metadata like Host, Content-Type, Authorization
3. Body: For POST/PUT requests, data goes in the body (JSON, form data)
4. Processing: Server parses the request, runs logic, possibly queries database
5. Response: Server sends “HTTP/1.1 200 OK” with status code, headers, body

HTTP is stateless—each request is independent. Servers don’t remember previous requests from the same client.

• Text-based message format (HTTP/1.1), binary in HTTP/2
• Methods: GET (fetch), POST (create), PUT (update), DELETE (delete), PATCH (partial update)
• Status codes: 2xx (success), 3xx (redirect), 4xx (client error), 5xx (server error)
• Headers provide metadata: Content-Type, Authorization, Cache-Control
• Runs over TCP (port 80) or TLS (port 443 for HTTPS)

• Built from: Socket — HTTP runs over TCP socket connections
• Built from: TCP Handshake — TCP establishes reliable connection first
• Builds into: API — REST APIs use HTTP as the communication protocol
• Contrasts with: WebSocket — WebSocket is bidirectional, HTTP is request-response
• Related: HTTPS — HTTP over TLS encryption
• Related: HTTP Methods — specific operations defined in HTTP
• Related: HTTP Status Codes — response outcome codes

• HTTP is text-based—binary data must be encoded (Base64) or use multipart
• No inherent state—every request must re-authenticate or send session tokens
• Headers have size limits, bodies can be arbitrarily large
• Without keep-alive, every request needs a new TCP connection (slow)