An Infinite is a mechanic in the Street Fighter series that is usually undesired.
Description[]
Ibuki performing her infamous "New Generation" Infinite on Alex. Notice how the only time he hits the ground is when he is stunned, and never has a chance to fight back.
Infinites are usually an unintended side effect from mechanics and attributes attacks tend to have. These can stem from normal Inputs, Unique Attacks, Special Attacks, and Super Combos.
Tactics[]
The Street Fighter series does not have many infinites available. This especially true post Street Fighter IV era where Capcom tries to keep the games as balanced as possible to both have as many viable characters as possible so people can choose the one they like based on design rather than gameplay, and to keep competitive integrity.
One of the ways Capcom have discouraged infinites in recent games is Damage Scaling. Where after a number of attacks each individual hit will do 10% or even less in some cases. Characters like El Fuerte have an infinite but many players who are capable of such high execution prefer to go for resets using his intense knockdown game after a while due to the high probability of a mistake combined with minimal damage being dished out each hit.
It should be noted that most of the games in the Marvel vs. Capcom series tend to have infinites as it's staple gameplay. These games are meant to be faster paced and feature less intense damage scaling to ensure games do not end in time overs.
Capcom tends to make fixing infinites during updates a priority even before they could patch the game. Ibuki's infamous New Generation infinite was fixed in the transition to 2nd Impact, and furthermore her Hashinsho was replaced with Yami Shigure, a super art that can not be followed up, in "Third Strike" to prevent further issues. Street Fighter X Tekken had patches to fix infinites for characters like Kazuya Mishima.