collecting

NOUN
10 LETTERS · STARTS WITH C

collecting is a valid 10-letter word worth 15 points in Scrabble and 21 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
C3O1L1L1E1C3T1I1N1G2
3 + 1 + 1 + 1 + 1 + 3 + 1 + 1 + 1 + 2 =15 PTS
DOUBLE WORD → 30TRIPLE WORD → 45
MEANING

What does collecting mean?