What is a module?
- allows you to extend Drupal without touching Drupal core code
- wraps related code into packages that can be used in other projects or shared with the entire community
- allows collaboration with the community with common standards
Different types of modules
- Glue modules: put little changes that you need to make to the way that Drupal is processed - not things shared on d.o, but created to achieve specific small things on particular site(s)
- Input filters: take input from users