CiviCRM integrates with what are arguably the three most popular open source CMS on the market today:
Each CMS has different advantages and disadvantages. Different people will give you better views on which is better. This chapter gives a quick introduction to each of them with the aim of helping you decide which one is right for your use case.
Of the three, Drupal is the most flexible and powerful, and has the best integration with CiviCRM. If you have complex CMS needs or envisage a lot of interaction between users on your website and your CRM, then Drupal might be the CMS for you. One negative is that the flexibility makes it harder for new users to get to grips with.
WordPress is by a wide margin the most popular of the three. It is considered to be very easy to use, especially for people that are not familiar with web technology. A lot of people know WordPress as a blogging platform rather than a CMS, but it is becoming more powerful and flexible with each release. One word of caution is that Wordpress integration is currently (as of April 2012) quite new. It will get more exenstive over the next couple of years but there is a fair amount that is not possible today.
Joomla! isn't as popular as WordPress, thought it is more popular than Drupal. Joomla is not as flexible as Drupal so isn't the choice if you want to offer extensive website integration. Many people say that Joomla is easier to learn than Drupal. Already having a website built with Joomla is another good reason to choose Joomla.
The following chapters in this section go into more detail about what is offered for each CMS.