Apache
Apache is an open source HTTP server which is developed by an open community of programmers working together under the Apache Software Foundation. The application is available for a wide variety of operating systems including Unix, FreeBSD, Linux, Solaris, Novell NetWare, Mac OS X, Microsoft Windows.
The Apache server was always a free and open source software, sometimes being regarded as the gold etalon of the genre, from at least 1996 being the most popular HTTP server.
As Apache plays a key role in the growth of the Internet around the world, it was seen at the beginning as the only viable alternative to the Netscape Communications Corporation web server, better known as Sun Java System Web Server. Apache is just one of the software used as a web server, along with nginx, LiteSpeed and many others.
Most current sites use programming languages that Apache does not know, and this requires an interpreter. This is why a server will have Apache and a PHP interpreter (+ others depending on language) and a database server (MySQL, PostgreSQL).
nGINX
Nginx is a free and open source web server that can also be used as a reverse proxy, load balancer, and HTTP cache. It can be used to deliver dynamic content using FastCGI but is also used to serve static content. It can also be used as a proxy, being useful, for example, for web servers written in Node.js that listen to localhost, adding more security and robustness. Nginx is the fastest web server currently available. First, stability is essential in an Nginx based environment and together with the extremely high response speed make it indispensable to the operation of any website, therefore vital at the web hosting level.
The main disadvantage of this software is not related to NGINX, but rather to market trends and customs.
NGINX is virtually not used in shared web hosting solutions for at least three reasons:
1. The .htaccess file is missing – this can indeed be a weak point in the eyes of most programmers.
2. The Apache Syntax Command.
3. Relatively new and makes it a problem to migrate existing sites.
The purpose of nginx is to get rid of useless consumed resources and to free them (where it is used as a reverse proxy).
For static content, where Nginx excels, files will be served quickly and directly to the customer. For dynamic content, such as PHP files, Nginx will transfer the request to Apache, which can process the results by returning to the previous page. Nginx can pass on the content of the client. Nginx also allows modules to be written as dynamic bookstores, allowing users to extend their functionality to their own needs. A set of modules already implemented can be found right on their site.
The idea of using nginx with ssl as a frontend for apache I think is perfect for the following reasons:
1. It behaves like a TCP offloader offering some extra protection for the web server (in case of DDoS attacks).
2. Decrease site access time (when compared to the simple apache solution with SSL).
As you can see, both Apache and Nginx are powerful, flexible and capable. Deciding which server is best for you is mostly a function of assessing the specific and testing demands of the standard you expect to see.