During drawing input, if the Auto Constraints Cursor mode is on, symbols are displayed confirming snapping to either of:
Coincident, depicted by the letter C
Coincident Point, depicted by the letter P
Horizontal, depicted by the letter H
Vertical, depicted by the letter V
Parallel, depicted by the parallel symbol: //
Tangent, depicted by the letter T
Perpendicular, depicted by the perpendicular symbol: ⊥
Equal Radius, depicted by the letter R
Note that Cursor and Global Auto Constraint modes can add noticeable time to sketch operations on very complex sketches, or with multiple sketches in a plane, so you can control whether or not you want them on (see Auto Constraints on the Constraints menu).