"We use Linux for all our mission-critical applications. Having the source code means that we are not held hostage by anyone's support department."

- Russell Nelson

Server

redhat Red Hat, Inc. (NYSE: RHT) is an S&P 500 company in the free and open source software sector, and a major Linux distribution vendor. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina with satellite offices worldwide. Red Hat has become associated to a large extent with its enterprise operating system Red Hat Enterprise Linux and with the acquisition of open-source enterprise middleware vendor JBoss.
centos CentOS is a free operating system based on Red Hat Enterprise Linux (RHEL). It exists to provide a free enterprise class computing platform and strives to maintain 100% binary compatibility with its upstream distribution.CentOS stands for Community ENTerprise Operating System.
opensuse openSUSE is a general purpose operating system built on top of the Linux kernel, developed by the community-supported openSUSE Project and sponsored by SUSE. After Novell acquired SUSE Linux in January 2004, Novell decided to release the SUSE Linux Professional product as a 100% open source project.
Apache Server The Apache HTTP Server, commonly referred to as Apache, is web server software notable for playing a key role in the initial growth of the World Wide Web. In 2009 it became the first web server software to surpass the 100 million website milestone
Nginx nginx (pronounced "engine-x") is a lightweight, high-performance Web server/reverse proxy and e-mail (IMAP/POP3) proxy, licensed under a BSD-like license. It runs on Unix, Linux, BSD variants, Mac OS X, Solaris, and Microsoft Windows.
apache_tomcat Apache Tomcat (or Jakarta Tomcat or simply Tomcat) is an open source servlet container developed by the Apache Software Foundation (ASF). Tomcat implements the Java Servlet and the JavaServer Pages (JSP) specifications from Oracle Corporation, and provides a "pure Java" HTTP web server environment for Java code to run.
jboss JBoss Application Server (or JBoss AS) is a free software/open-source Java EE-based application server. An important distinction for this class of software is that it not only implements a server that runs on Java, but it actually implements the Java EE part of Java.