There are many different web application servers to choose from. In some cases, depending on your development platform, you are restricted to a limited selection of web servers. In other cases, you will put together many different web application servers to provide a cohesive site. For example, your site uses Wordpress and you are using a Java based forum. You will most likely incorporate elements of Apache web server in addition to Tomcat to serve up your content. Also your choice in hosting provider will also limit your choices and may also dictate your development platform. For example, many shared hosting providers implement the venerable LAMP stack (Linux Apache MySQL, and PHP).