Both Emily and Tanner are micro-chipped. I figured that if I ever move and they were to get out this would increase the probability that I would get them back. Besides Emiliy won't wear a collar, so I had no other way to identify her and I had thought of moving to England at one point (where it is mandatory to chip your cats).

Sometimes the local SPCA'a will provide low cost chipping as a special at their adoption days and this is one way to get your pets done.

Although there are two brands of chips on the market, the scanner technology will read both without difficulty (which is changed from a few years ago). Most American shelters (at least in the biger centers) now automatically scan when animals are brought in.