Crest:
Tai - Courage
Sora - Love
Matt - Friendship
Izzy - Knowledge
Mimi - Sincerity
Joe - Reliability
TK - Hope
Kari - Light

The crests are what makes the Digimon Digivolve to their next level. The tags is for holding the crests. All of them have found their crests, but not all got them to Digivolve all the way. For it to work, the Digivice's light shines up and goes through the crest.