Can you tell me what is time based workflow in Salesforce?

Adding some points:

Salesforce users have an option to Monitor their time based workflow actions pending in the queue. In order to do that, they can follow these steps:
1. From Setup, enter Time-Based Workflow in the Quick Find box, then select Time-Based Workflow.
2. Click Search to view all pending actions for any active workflow rules, or set the filter criteria and click Search to view only the pending actions that match the criteria.

Disadvantage:

Time based workflow actions will not always execute at the exact time displayed in the Monitoring setup menu. Instead, they are batched and executed every 15 minutes. Considerations for Time-Dependent Actions and Time Triggers still apply. Therefore the expectation for the execution of time based workflow actions should be within 15 minutes of the scheduled time unless the Time Trigger per hour limit is exceeded, which will push the batch to the next hour.

Thanks