As with any Apache module, there are a number of ways to install mod_rewrite. Fortunately, the vast majority of third-party distributions of Apache come with mod_rewrite installed and enabled. This is a reflection of the popularity and power of the module.
However, since mod_rewrite was added to the main Apache source distribution several years after the initial release, it is not part of what is enabled by default in an installation from source. Thus, whether you already have mod_rewrite installed and what you will need to do to get it working will vary depending on how you installed Apache.
A great amount of complication ...