Production Work center activities are optional sub-sets of work center departments. Activities may be defined prior to establishing work centers, and then used as more detailed actions within a work center. Each of these activities may be assigned a separate hourly charge rate.
Please note: As of 03/03/2016:
We are actually in the process of implementing optional routing steps in place of activities. We are working to simplify and flatten the process to make it easier for everyone.
Presently, you can still choose to setup activities if desired and then decide if you want to track production through activities or not. With the current activity setup this decision is universally applied for all work centers and work orders.
With the optional routing steps that we are implementing, you would still have to decide if you want to add activities or not (optional steps), but now you would be able to decide on the fly if you want to track production through those steps. It also means that you would have fewer places to maintain in setup. | 
