Chunked encoding involves transferring the body of a message as a series of chunks, each with its own chunk size header.
This defined process means that an application-generated entity body, or a large entity body, can be sent in convenient segments. The client or server knows the chunked message is complete when the zero length chunk is received.
The body of a chunked message can be followed by an optional trailer that contains supplementary HTTP headers, known as trailing headers. Clients and servers are not required to accept trailers, so the supplementary HTTP headers should only provide non-essential information, unless a server knows that a client accepts trailers.
To use chunked transfer-coding, both the client and server must be using HTTP/1.1. A chunked message cannot be sent to an HTTP/1.0 client. The requirements that apply to chunked transfer-coding and the use of trailing headers are defined in the HTTP/1.1 specification
