I want to track who has donated to our non-profit through a time period (2010-2013) but want to exclude donors who have given since 2014-present.
First create 2 groups, one for donors for time period 2010-2013 and the second for period 2014-present.
Then go to Search - Custom Searches - Include / Exclude Search
Then choose group 1 as "include group" and group 2 as "exclude group" and click Search.
The result will contain exactly the people you want. It would make sense to add them to a third group, so you can send them a Mailing or whatever you want with them.