# RESTful APIs
RESTful APIs, or REST (Representational State Transfer)
is a software architectural style allowing the requesting systems
to access and manipulate textual representation of Web resources
by using a uniform and predefined set of stateless operations.

## Architectural Constraints
### Client-Server Architecture
Separating the UI concerns from the data storage concerns improves
* Portability of UI across multiple platforms
* Scalability (by simplifying the server components)

### Statelessness
Session states are not stored on the server,
but maintained by and sent from the client.

### Cacheability
Improve scalability and performance by caching appropriately.

### Layered System
Improve performance (via caching) and security by intermediary servers.

### Code on Demand (optional)
Transfer executable code.

### Uniform Interface
* Resource identification in requests
* Resource manipulation through representation
* Self-descriptive messages
* Hypermedia as the engine of application state

## The API
### URI
Base URI to collection resource, e.g. http://api.example.com/collection/

Member resource: http://api.example.com/collection/item42

### HTTP methods
* GET: retrieve resource representation
* POST: create member resource
* PUT: replace representation of resources
* PATCH: update resource representation
* DELETE: delete resource representation