A 'Crowd' is a group of people who share common topics and lifecycles.
In the ATC platform a 'Crowd' is a group of people who share common topics and lifecycles.
Those is your crowd will be determined by the scope of the project that you are working on.
You may be working on something that applies to your whole organisation - such as Customer Service - in which case your crowd will be everyone in your organisation.
Or you may be working on a project with a specific focus - such as development of a product - in which case your crowd will be those with an interest in that project.