Select Linked helps you select faster and more efficiently in Edit Mode, so you spend less time manually selecting and more time creating stuff (like the cool rusty car by Quaz30 on Sketchfab that you see in this video).

This video quickly goes over every option: Select Linked, Deselect Linked, Select Linked under Cursor, and the options Material, Seam, Sharp, UV, Normal and how to select none or multiple of those.

Finally we look at the Select Linked Flat Faces option.