1、http/0.9
http0.9 only one method: information get, no other description data header, the server is sent, the TCP connection is closed, is different from the current version 1.1, a TCP connection, multiple requests can be sent
2、http/1.0
Added a lot of other commands, post, put, header
Increase the status code and header
Multi-character set support, multi-part transmission rights, cache, etc.
3、http/1.1
Supports persistent connections, the previous version is a http request to establish a TCP connection
Increase the pipeline, in the service before the end, before a request is processed and been sent back to send a second request
Increase the host and some other commands in the same physical server can start more than one service, you can host distinguish which specific service request
4、http/2.0
Data is transmitted in binary mode, most of the previous version are strings, http2 are to be transmitted Chen
A plurality of the same TCP connection request transmitted in the inside, at the same time can be returned, it is no longer necessary in order to
Header compression and push functions to improve the efficiency of the function
Header compression: request and response headers in the header information is stored as a string, it must complete transmission, now the information is compressed
Push function: http client sends a request, the server responds, the server can now take the initiative to send something to the client. For example, a previously loaded first html, then loaded inside js, css, the server may now html, transmitted together js, css to the client
https protocol: a more secure protocol