Why need CPL filter for camera lens?

1.Protection for the front lens element
It protects the front lens element from finger prints, scratches and dirt destroying.

2. Cut off reflections and glare
It cuts off reflections and glare from glass, metals or shiny surfaces that would damage image quality, this works in the same way as polarized sunglasses.

3. Make colors more saturated
It cuts reflections from surfaces like leaves, grass or walls, making colors appear saturated, and shadows appear blacker.