Information to Include on Tag

Regardless of the material you choose, following is the information you should put on the tag.
Pet's Name - This will help whoever finds your pet comfort him when he is lost and can hear his own name.
Phone Number - List your most frequently used phone number.
Medical Information - Including medications may save your pet's life so a veterinarian can give him his medication until you can be reached.
Your Name and Address - This information is optional but can be helpful.

High Tech Pet ID Tags
Technology has also improved pet ID tags. A QR code pet ID tag is a tag that links to a website via a QR (quick response) code, which is a scannable 2D-dimensional bar code imprinted on a tag. This type of tag can get your pet home faster and safer than a traditional ID tag.
If you wish, you can still have your phone number engraved on it, but whoever finds your pet can also use any smartphone or computer to access your pet's online profile that contains critical data you deem necessary. Many QR code pet ID services will also send you the GPS location of your pet.