text: Friction is when there is contact between two surfaces.  If you put your hand on a table and press down and forward, your hand will slide, but it won't slide as easily if your hand were greased with butter, for example.  Friction is what keeps your hand from sliding smoothly.\n\nIt has to do with gravity, because gravity pulls your hand down on the table (in addition to the pressure you put on it).\n\nIn more detail, friction is actually an opposing force.  Your hand wants to slide in the direction you're pushing it in, but it can't as easily because the force of friction is pushing it BACK AGAINST YOU.  The friction opposes (doesn't let it happen easily) your pushing.\n\nHope that helped.