Interrupting is to stop attacks from being started or continued. Moves that has a slow cooldown frames is quite interruptible. Also, in a crowd area, moves that has small range and are non-multiple are also interruptible. To interrupt, a fast move should be used, probably move that are non-interruptible(see below). If a character catches the opponent and the opponent has a fast jump attack(like Deep or Rudolf), the combo after catching maybe interrupted by using jump attack.
Certain attacks that are not easy to be broken is called non-interruptible. The only perfect attack move, which is non-interruptible, is Davis's Dragon Punch. Other attacks which have fast warmup frames and have long attack range (like Strike) or attacks which will switch the user into defend mode (like Monk's Shockwave) is also quite non-interruptible. Another exception is Louis. When Louis turned into LouisEX, he will be invincible and it is also non-interruptible.