Frameskip is a method used by Capcom fighting games make the gameplay faster. It began with the sped-up bootlegs of SF2 World Warrior and Champion Edition and became official in Hyper Fighting. Almost all the 2D (sprite-based) games up through Capcom Fighting Evolution used it, with the notable exception of 3rd Strike and the other CPS3 games.
How it works: A certain number of frames are played normally, then one frame is dropped, then some more normal frames, then another drop, and so on. During a dropped frame, everything in the game world continues to happen, but it doesn’t get displayed. In the span of one real-life frame, two in-game frames get processed by the machine. This has the effect of making everything except music and sound effects faster: startup, recovery, impact freeze, walk speed, charge requirements, background animations, etc. all get faster.
