HTTP Status codes are issued by a server in response to to the client's request. These status codes (as part of the response message) helps to inform clients around the result of their REST API request.

RFC 2616 defines the Status-Line syntax as shown below:

All HTTP response status codes are separated into five classes (or categories). The first digit of the status code defines the class of response.

Category

Type

Description

1XX

Informational

The request was received, continuing process

2XX

Success

The request was successfully received, understood, and accepted

3XX

Redirection

Further action needs to be taken in order to complete the request

4XX

Client Error

The request contains bad syntax or cannot be fulfilled

5XX

Server Error

The server failed to fulfill an apparently valid request

Following are some commonly used status codes.