Club Path
The left/right direction the club head travels through impact.
What it is
Club path is the horizontal direction the club head is moving at impact relative to your target line. A positive value is an in-to-out path (to the right for a right-handed golfer); a negative value is out-to-in (to the left).
Why it matters
Club path, combined with where the face points, decides which way the ball curves. A path that doesn't match your face angle is the root cause of most slices and hooks.
How to improve it
Use alignment and swing-direction drills to shallow or steepen the path as needed. Many slicers benefit from feeling a more in-to-out path; chronic hookers may need the opposite.