Finger tricks
Finger tricks are a tool that involves the cuber using his fingers to pull off the moves of an algorithm faster. The goal is to reduce the number of times the cube needs to be regripped (to take one's hand off of a side to change the position of the hand on the cube for future moves), and to overlap move times (meaing that two moves are being performed at that same time, overlapping and thus shortening their execution time). The less regrips, and the more overlapped moves, the faster the algorithm can be performed.
Finger tricks also influence which algorithms are chosen for certain solution cases because certain algorithms may be easier or faster to perform with finger tricks than others. Because of this, the ability (or inability) to do finger tricks greatly influences a cuber's style and speed (as testified to by Dan Knights). Finger tricks are also the reason that corner cutting is considered an important quality of a good speedcube. It is because of corner cutting that moves are able to be overlapped with finger tricks.
The most common algorithm connected with finger tricks is the sexy move, R U R' U'.