Definition: Grinding is the name for sliding along an edge (such as a curb, bench, rail, coping, etc.) using your trucks instead of your wheels or deck. Depending on which trucks are being used (front or back), and what direction you are moving, there are many different types of grinds, such as the 50-50, the 5-O, the Nosegrind, and many others.
Make sure not to confuse a grind with a slide. Slide is the name for doing this exact same activity, only using the skateboard deck instead of the trucks.
Examples:
"You can tell a popular skateboarding spot by the black and metal grind marks along its curbs. Skaters often put wax on curbs to help grind further, and that adds to the marks."
