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HTTP Overview (MDN)
Definition of HTTP, principles and basic properties of the protocol.
HTTP is an application layer protocol that has become the basis of the World Wide Web and most web APIs. It describes the exchange in a request → response format, while remaining simple and extensible for different scenarios.
Key HTTP Properties
Client-server model
The client initiates a request, the server responds with a resource or status.
Stateless
Each request is independent, and state is stored outside the protocol.
Extensibility via headers
Headers allow you to add metadata, caching, and content negotiation.
Intermediate nodes
Proxies, caches and gateways help scale and speed up delivery.
What does an exchange look like?
The request contains the method, path and headers, and the response contains the status, headers and payload. This simple form provides versatility and compatibility between clients and servers.
HTTP request ↔ response
HTTP is a clear pair: request from the client and response from the server.
Message structure
- Method (GET, POST, PUT)
- URI / resource path
- Headers
- Body (optional)
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Evolution of HTTP (MDN)
History and key development milestones of HTTP/1.1, HTTP/2 and HTTP/3.
The evolution of HTTP
The protocol evolved from simple text exchange to optimization of performance and stability.
HTTP/1.1
1997 (RFC 2068), updated 1999 (RFC 2616)Standard "text" web
- Persistent connections and pipeline
- Caching and chunked transfer
- Often requires multiple connections
HTTP/2
2015 (RFC 7540)Binary framing
- Multiplexing streams on a single connection
- Header compression (HPACK)
- Reduced page loading delays
HTTP/3
2022 (RFC 9114)QUIC over UDP
- Fast handshake and less blocking
- Avoiding TCP head‑of‑line
- Best Mobile Network Experience
Why is this important for System Design?
- HTTP defines the API format and affects latency, caching, and client behavior.
- The choice of protocol version affects connection efficiency and scalability.
- Understanding constraints helps design resilient and performant services.