What is HTTP/1.1?
HTTP/1.1 is one of the versions of the Hypertext Transfer Protocol (HTTP), which is used for transmitting content such as HTML between clients (e.g., web browsers) and web servers. HTTP versions have evolved over time, with HTTP/0.9 released in 1991, HTTP/1.0 in May 1996, HTTP/1.1 in January 1997, and HTTP/2 in May 2015.
The first version, HTTP/0.9, was extremely simplistic, with no specifications for responses and only the GET method available. HTTP/1.0 introduced response headers and added POST, PUT, DELETE, and other methods.
HTTP/1.1 further expanded functionality by supporting additional methods and introducing name-based virtual hosting. Virtual hosting allows multiple virtual web servers to run on a single physical server, assigning multiple hostnames to the same IP address. In HTTP/1.1, the Host header enables specification of the target virtual host for a request.
To address the challenges of increasing web content richness and longer response times, HTTP/1.1 introduced features such as KeepAlive, which maintains the server connection to process multiple requests without reopening connections, and pipelining, which allows clients to send multiple requests without waiting for responses. These developments reduce TCP connection overhead and shorten response times.
Currently, HTTP/1.1 is the most widely used version. However, HTTP/2 further optimizes TCP resource utilization, improves performance, and enhances security.