The prusik knot is one of the most popular slide-and-grip knots. It's the most popular slide-and-grip knot, not because it works the best but because it is the easiest to tie. Unlike the other slide-and-grip knots, the Prusik works in either direction, which could be good or bad depending on your situation.
The prusik is easy to tie and to untie.
The prusik doesn't release as easily as some of the other slide-and-grip knots.
The prusik knot can only be tied with a prusik loop.
The prusik loop must have a smaller diameter than the climbing rope for the prusik knot to grip.