HTTP
The request-response protocol of the web.
Also known as: HyperText Transfer Protocol, HTTP protocol
HTTP is the protocol your browser and apps use to talk to web servers. It works as request and response: a client asks for something, the server answers. Then the exchange is over.
A request:
GET /products/42 HTTP/1.1
Host: shop.example.com
Accept: application/jsonand its response:
HTTP/1.1 200 OK
Content-Type: application/json
{"id": 42, "name": "Kettle", "price": 2999}Each message has the same parts:
| Part | Request | Response |
|---|---|---|
| Start line | method and path (GET /products/42) | status code (200 OK) |
| Headers | Metadata: what I accept, who I am | Metadata: content type, caching |
| Body (optional) | Data you send (a JSON form) | The content returned |
Key properties
- Client-initiated. The server doesn’t speak unless asked (for push-style updates you need other tools such as WebSockets).
- Stateless. Each request stands alone; the server doesn’t remember the previous one. Things like login rely on cookies or tokens sent with every request (see session).
- Plain text, in version 1.1. HTTP/2 and HTTP/3 are more efficient on the wire but keep the same ideas, so what you learn here still applies.
- Not encrypted by itself. HTTPS adds that.
See it yourself
curl -i https://example.comor open the network tab in your browser. Reading real requests and responses is the fastest way to learn HTTP, and the first step when an API call “doesn’t work”.