Chips allow you to make unlimited changes to your squad. You get two chips per season, which you can play once each throughout the competition.
The Wildcard gives you the chance to change your squad as much as you like. When you play it you can make unlimited free transfers, and any players you transfer in will stay in your squad once that matchday has finished.
Limitless gives you the chance to change your squad for one matchday only. When you play it, you get unlimited free transfers for that matchday with no budget restrictions. Once the matchday has finished, your squad will return to how it was before you played Limitless.
In both cases, the normal rules for automatic substitutions, manual substitutions and captain changes still apply, as well as formation constraints and the number of players you can pick from one team.
If you’ve already made transfers ahead of a matchday and you then play a chip, the transfers you’ve made previously will be cancelled, along with any points deductions.
You can’t play your Wildcard or Limitless chips when you’re selecting your squad for the first time, since you have unlimited free transfers anyway. You also can’t play them ahead of Matchday 7 (the round of 16 first leg) for the same reason.