How does a server distinguish between two browser applications running simultaneously accessing the same server to get http files?

A server distinguishes between two browser applications accessing it simultaneously through the use of unique session identifiers, typically stored in cookies or URL parameters. Each browser instance sends its own headers, including the User-Agent string, which can also help identify the client. Additionally, the server maintains separate session state based on the IP address and port, enabling it to manage requests from different sources effectively. This ensures that each application's requests are handled independently, even when they originate from the same machine.