Boosters are special items that can be used on a level to help you win. There are currently three different boosters available.

Target Booster - Will allow you to choose a single tile on a level to be destroyed.
Cross Blast - When activated, will allow you to clear the row and column of the selected item in a cross shape.
Pet Charge Booster - Activating this and tapping on the pet will instantly allow it to move without being being fed.

Each player will receive 1 of each type of booster after completing certain levels. After they have been used you can purchase more for gems or in special offers.