Many photographs use the UV filter as a lens protector and therefore leave the filter in place almost permanently. A UV filter will not protect the lens from rough handling but will help with general dust and smears.
A filter is flat and can be removed for easy cleaning on both sides. If the filter does get scratched either by dust or the act of cleaning then a UV filter is much cheaper to replace.
To learn more about UV filters and other FREE photography lessons visit www.dftours.com.au/free-photography-lessons.