Your security key provides access to this API and will need to be provided on every request.
A category is a collection of groups. A site may have multiple categories. Examples of categories include Department, Division, Job Title, Shift, etc.
This is a solution available to a specific and limited number of clients that allows multiple sites to share certain resources.
A group is a collection of users within a category. A site may have multiple groups per category. For instance, if Job Title is the category, then the groups are pre-defined values that could include Accountant, HR Manager, Firefighter, Lieutenant, etc.
A site is a collection of applications to manage, modify and track users, training, credentials, events and tasks.