Triangle files are used for cleaning corners and filing material with angles less than 90 degrees. Triangular files are tapered to the point.
Smooth cut files are finer files and have the most teeth per inch. They are used for detailing and fine finishing work.
Double cut files consist of two sets of teeth crisscrossing each other at opposite angles. They are used for heavy stock removal.
A tang is the tapered end of the file that can either be used to hold the file or inserted it into an optional handle.