SilverStripe modules are a type of add-on (the other kind is themes) that provide extra functionality to SilverStripe. The core of SilverStripe functionality strives to include only what’s necessary. Nonetheless, we find that we almost always use a handful of modules with particularly widespread applicability.
I’ve seen lots of comparisons between SilverStripe and other CMSs like Drupal, but most of them are either very high-level, or mostly editor-centric. So, I thought I’d explain why we chose SilverStripe over Drupal, from the point of view of a web developer.