A filtered data extension is generated by filtering criteria in fields, filters, and measures from a source data extension to identify a particular group or target audience. Typically, you will filter the data from your Master Subscribers Data Extension. 

If using user ingestion or SFTP to import your data, you should identify the field and the field criteria prior to importing your data. 

In Email Studio, follow the instructions to create your filtered data extension.

1. Hover over Subscribers.
   
2. Click Data Extensions.
   
3. Click Create.
   
4. Select Filtered Data Extension.
   
5. Click OK.
   
6. Select a standard data extension to filter as the source data extension (i.e. your Master Subscribers data extension).
   
7. Click OK.
   
8. Drag your chosen Fields, Filters, or Measure from the left column to the Create Filter canvas. 
   
   NOTE: Be sure to choose an operator that makes sense with the type of field you chose. For example, do not use the less than operator with a text field. For attributes with type equal to date, only the following operators are supported: is equal to, is not equal to, is greater than, and is less than.
   
9. Select an AND or OR operator. You can group your criteria by hovering over the grouping operator so that it turns a darker blue, and clicking to change the operator. If you choose AND, the record must meet all criteria to be included in the group. If you choose OR, the record must meet one of the criteria, not necessarily all criteria, to be included in the group.
   
10. Click Save & Build.
    
11. Enter a Name for the filtered data extension.
    
12. Enter a Description for the filtered data extension.
    
13. Select a folder in which to store the filtered data extension. Or select New Folder to create a folder to store the filtered data extension.
    
14. Click Save.
    

Filter a Filtered Data Extension

A filtered data extension is generated by filtering fields, using existing data filters, or measures in Email Studio. By creating a new filtered data extension, you can further refine the filter to target a more specific set of subscribers.

There are a few ways to create a filtered data extension from another filtered data extension:

• You can create a new filtered data extension from a saved or existing data filter. For example, if specific filter rules are used frequently, you can save the rule as a data filter and continually use this saved data filter as a starting point for other filtered data extensions.
  
• You can also copy an existing data filter. The copied data filter can be used as a starting point for a new data filter. The new data filter can be edited and more rules can be added.
  

NOTE: Previously created, before the new drag & drop segmentation functionality, data filters from filtered data extensions continue to be supported, but creating a new data filter from a filtered data extension are not supported with the new drag & drop segmentation functionality.

Source: salesforce.com