Web servers are servers operated by providers for web hosting. They are connected to the Internet or intranets and provide websites and other online information that can be requested, for example, at the request of a browser, that is the web client, using the Hypertext Transfer Protocol (HTTP) or HTTPS.
If, for example, a certain website is to be called up in the web browser, the internet address entered in the browser is sent to the name server, which determines the IP address from the domain name. Then the HTTP client of the web browser establishes a TCP connection to the HTTP server of the web server and makes a request to it, in which it requests a website. Since complete websites consist of various HTML texts, graphics, flashes, photos or videos, the client must make a separate request for each file, which the web server answers by transmitting the files. The HTTP server sends the requested files to the HTTP client, which displays them on the screen via the HTTP interpreter. After receiving the complete website, the TCP connection is cleared again.
The information provided on web servers includes HTML pages, text and graphic documents as well as dynamic database-based pages. In addition to the delivery of websites, web servers can also perform security-related functions and secure data exchange via the HTTPS protocol, they manage cookies and give status messages to the browser via the HTTP status code if, for example, a website cannot be accessed or no longer exists ,
Operating systems of web servers are Unix, Linux or Berkeley Software Distribution (BSD), Apache is used as common public domain software, but also commercial software such as the Internet Information Server (IIS) from Microsoft.