There are two types of penalties. Ones that happen before the snap and ones that happen after the snap.
Ones that happen prior to the snap depend on if the linemen are set in their stance and move too soon or wide receivers make a motion before they are supposed to or a receiver is lined up one too many to the line of scrimage, and others.
After the snap happens if receivers are bumped after 5 yards or so, offensive or defensive pass interference, offensive holding, illeagal block in the back, punching, etc...