The default input types in Drupal strip out unapproved HTML tags and optionally format links with
Note that an unfiltered input type will not support PHP; you must enable the PHP module for this. Once you enable the PHP module, it will create an input type specifically for PHP. The PHP block will allow unfiltered HTML, but may present an unnecessary security risk.
To create an unfiltered input type in Drupal 7, do this:
Go to Configuration > Content Authoring > Text Formats
You should see the default text formats appear.
Click add new text format and give your new text format a name, such as “Unfiltered HTML.” Choose the roles that will be allowed access to this input type. Be aware that allowing untrusted users access to an unfiltered input type may have security implications. Don’t check anything under Enabled Filters. Click Save Configuration.
That’s it. Your input type is now ready for use.