HTTP is a method for encoding and transporting data between a client and a server. It is a request-response protocol i.e., clients issue requests and servers issue responses with relevant results.
HTTP is self-contained i.e., it contains all relevant information within the HTTP message to traverse intermediary devices like load balancers or routers. The self-contained nature also allows responses to be cached and sent when needed.
HTTP API Methods
| Verb | Description | Idempotent* | Safe | Cacheable |
|---|---|---|---|---|
| GET | Reads a resource | Yes | Yes | Yes |
| POST | Creates a resource or trigger a process that handles data | No | No | Yes if response contains freshness info |
| PUT | Creates or replace a resource | Yes | No | No |
| PATCH | Partially updates a resource | No | No | Yes if response contains freshness info |
| DELETE | Deletes a resource | Yes | No | No |
*Can be called many times without different outcomes.
HTTP is an application layer protocol relying on lower-level protocols such as TCP and UDP.