Drupal

Filters are used in Drupal to change the content of the text of a node when it is viewed. The important thing to note is that Drupal filters should never alter the actual content of the node itself. Instead, when a node is saved it stores the output of the filter in the cache_filter table and displays this content the next time the node is viewed. This is useful because it doesn't mess about with the original text, and it speeds up the displaying of the node by running the filters once, rather than every time the node is loaded.

However, there is one thing that you should watch out for when creating your own modules. If you are using any data from other tables in your filters then you will need to clear the cache when this data changes.

Drupal is a CMS system that can be freely downloaded and used from the Drupal website. It is not an object orientated PHP driven system and so everything is available through function calls and variables.

I have heard that the learning curve on developing Drupal is quite steep, but once you get around this initial hurdle the whole thing is pretty simple. This ease of development means that it is possible to take an idea and use Drupal and all its features as the CMS behind your idea, thus saving you time on your project development.