Is it possible for a trigger to test the data to be inserted and if it doesn't meet specific criteria not insert the data at all?

I have an application that writes a lot of data to my table. I don't have control over this application and it writes a lot more data then I need. So I'd like to have a trigger that doesn't allow certain records to be written at all. I can't seem to find anything in the documentation that describes what I'm looking for.

Thanks