Web server market is dominated by Apache HTTP server that enjoys its status because of its open source nature and because of its role in bringing the masses to the world wide web. Without it, we may not have had so many web hosts and web sites. However, its memory footprint has been a concern until today.
Nginx is the second largest in terms of Web Servers Market Share. While Nginx is still open source, the constant upselling of its commercial subscription may not be welcomed by everyone. Don’t get me wrong. I use Nginx too for its low memory footprint and its efficiency in serving static files.
Microsoft’s IIS is third most popular web server. It is rock solid, having its own use cases.
OpenLiteSpeed is very limited in its functionality.