Both Daisy and Venus have collars. i put a tag with my name and address AND telephone on it, just in case. (For example, for Venus' collar, the first line reads: Venus' Mom - Shirley)
Daisy is microchipped, and i finally got an answer from the rescue center that Venus is not. So, i have to get her microchipped asap.
They are both indoor kitties, but i do bring them out with me, like taking short car rides, grocery shopping, parks,etc. So, i put on their collars. This way, they are easily identifiable.
When they are at home, they don't wear collars, for comfort's sake.
Actually, i love getting the cool and neat collars fo my babies. My favorite is a soft collar with piano design. It is Daisy's.