Permissions are a set of activities that a user is allowed to perform on a website.
If you think about it, you probably deal with this all the time.
The best example is probably your ONID account. You are allowed to log in to your ONID account, and you can view and change quite a few different things related to your account because you are permitted to do these things on your account. You are not generally permitted to go onto your colleague's account and make changes, though. In most cases, you and your colleagues might have some time of role called Member or User.
Sometimes, though, things go wrong with our accounts and we need someone who is permitted to work across the whole system to come in and fix it for us. This type of user might be called something like Administrator. It's this person's responsibility to fix things and provide support service to the users of the system. They are permitted to go into individual accounts on an as-needed basis to provide the service that regular users need.
Our OSU Drupal installation has five default roles, which are explained in the Roles section of this manual. Each one of these roles has a different set of permissions.
For example, an author is permitted to create and edit content, create and edit menus, upload media, etc.
An author can't use PHP code, though. This is a special type of code that can actually destroy your Drupal site if it's in the wrong hands. The only roles that are allowed to use PHP code are advanced authors and administrators.
An administrator on an OSU Drupal site is actually capable of changing permission sets, and even creating new ones for custom roles that are added to the site. Read on to find out more about creating custom permission sets.