Typically, a view displays all the tasks or resources in your project. That’s okay when you really want to see them all, or if there are so few tasks or resources that you can see them without much scrolling. Often, though, a project contains many tasks or resources, subsets of which share certain characteristics. For example, some tasks might share the characteristic of being completed. Others might share the characteristic of being summary tasks. Likewise, some resources might share the characteristic of being overallocated.
If you want to see information about only tasks or resources that share certain characteristics, you can apply a filter. For each sheet, chart, and graph view (except the PERT Chart and the Task PERT views), a filter determines which tasks or resources Microsoft Project displays or highlights. A filter contains instructions, called criteria, that specify the conditions under which a task or resource will appear. You change the filter applied to a view when you want to see information about different tasks or resources in the current format.
If none of the filters provided with Microsoft Project meets your information needs, you can create a new filter or modify an existing one by customizing a filter’s criteria.