Chain Combos are performed through the repeated use of a light kick or punch, followed by a stronger attack (including unique attacks and special attacks) or special move immediately after. (e.g. jab into fierce, jab into roundhouse, etc.) Most characters in Street Fighter Alpha have one move that can initiate a Chain Combo, due to the speed it requires.
The Chain Combo system was almost completely removed in the game's sequel, Street Fighter Alpha 2, as most of the cast's light attacks were made slower in order to balance out the game; only Guy and Gen retain the ability to perform a Chain Combo throughout the series.
Street Fighter X Tekken uses a Cross Rush mechanic that is performed similar to a Chain Combo, with regular attacks used in increasing strength order to create a combo that automatically launches a foe; if it lands successfully, the user will also tag their partner in to continue the combo.