JIRA comes in two distributions: the standalone and WAR distributions. The only difference is that the standalone distribution comes bundled with Apache Tomcat, an in-memory database, and Java, if you use the executable installer version. The WAR distribution, on the other hand, contains only the JIRA web application.

As you can see, the standalone distribution comes with everything required to get JIRA installed. The standalone distribution comes in two flavors: an executable installer and a ZIP archive. The executable installer provides a wizard-driven interface that will walk you through the entire installation process. It even comes with a Java installer to save you some time. The ZIP archive flavor contains everything except for a Java installer, which means you will have to install Java yourself. You will also need to perform some post-installation steps manually, such as install JIRA as a service. However, you do get the advantage of learning what really goes on under the hood.

The WAR distribution is for more advanced users who are familiar with the Java EE application deployment model. With the WAR distribution, you have to make the necessary changes to the configuration files, build your own deployable JIRA, and then deploy it to an application server; in this case, Tomcat. The advantage of using WAR distribution is that it is very easy for you to version control all the changes you make to the standard distribution files, which makes future upgrades much easier.