Filters let you ignore temporarily tasks you don't care about. They help you focus on the tasks that need doing.
You can set filters for anything you can search for. Tags, group, due date, priority, task summary, and so on.
Many filters will affect the tasks you create. For example, if you filter for a particular group, then any tasks created will be put into that group.
You can see your current filters with filter.
You can clear all your filters with filter clear. You can clear individual filters with filter clear filter number. The filter number can be negative, meaning "count from the end."