There are many different types of item, avatar or experience sets for you or your pets to collect. Once collected they cannot be removed. The more that you collect, the more you will be Rewarded.
The Invisible Fairy rewards you for the number of Experiences you have collected. There are many other Collections that you can complete for even more Rewards.
If you add the Drew Giftbox to your collection, if you have the clothing and colours Drew needs, you will be able to automatically dress your doll in the clothing Drew asks for, in the colour he asks for, in just one click!
The Seasonal Fairy also rewards you for every giftbox that you collect