There is only one file type that uses the .IT extension:
Impulse Tracker Module
Music module created by Impulse Tracker, an audio tracking program; contains a sequences of notes, or patterns, that play back sound samples which are also stored in the file; similar to an .S3M file, but supports more data per pattern and higher quality samples.
Various programs can open IT files, including Impulse Tracker, Nullsoft Winamp, Schism Tracker, CocoModX, and MikMod. You can also open the files in Audacity with the FFMPEG v2.2.2 or later installed.
Updated: April 26, 2019