Apache or nginx

[jdunhin]

Apache or nginx? It sound like nginx is taking over on the servers. Is it really faster?

 

[CharlesByrd]

Apache is a process-based server, while nginx is an event-based web server.
Nginx and Lighttpd are probably the two best-known asynchronous servers and Apache is undoubtedly the best known process-based server. The main advantage of the asynchronous approach is scalability. In a process-based server, each simultaneous connection requires a thread which incurs significant overhead. An asynchronous server, on the other hand, is event-driven and handles requests in a single (or at least, very few) threads.
While a process-based server can often perform on par with an asynchronous server under light loads, under heavier loads they usually consume far more RAM which significantly degrades performance. Also, they degrade much faster on less powerful hardware or in a resource-restricted environment such as a VPS.
Pulling numbers from thin air for illustrative purposes, serving 10,000 simultaneous connections would probably only cause Nginx to use a few megabytes of RAM whereas Apache would probably consume hundreds of megabytes.