How to put a tag on a collar (and make sure it stays on)

• Split ring: the double loop of wire, like a keyring. The most common fitting and one of the most secure, because it has no opening to come undone, but it's fiddly to get on.
• S-hook: a small S of metal you squeeze shut with pliers. Quick to fit, but it can be pulled open again, so check it's fully closed.
• Clip or lobster clasp: easy to swap between collars, but a clip can snag and come undone, so it's the least secure for everyday wear.
• Slide-on tag: threads onto the collar itself and sits flat, so it can't swing, catch or fall off. It has to be the right size for the collar.
• Riveted plate or embroidered collar: nothing to come off at all, which is why they're popular for dogs that swim or play rough.

• Push the edge of a coin, a small flat-head screwdriver or a butter knife between the two loops at the end of the ring to open a gap. Split-ring pliers, which cost a few pounds, make it much easier.
• Slide the tag's hole into the gap, then turn the ring round until the tag has travelled all the way along the coil and hangs from the ring properly.
• Put the ring onto the collar's D-ring, the metal loop the tag hangs from, the same way.
• Give the tag a firm tug. It shouldn't be able to slip back out through the gap.

If the ring is small and stiff, work slowly. Split rings are hardened steel, and it's easier to lever them open a little at a time than to force a fingernail in.

Hang the tag from the collar's D-ring. If the collar has two rings, keep the tag on the one you don't clip the lead to: the lead clip rubbing against the tag's ring on every walk wears it through faster, and the tags knock together less. Our guide on stopping a dog's tag jingling has more on that.

For a cat, use a quick-release (snap-open) collar, which Cats Protection describes as the safest kind because it pops open if it gets caught. Hang the tag from the collar's ring so nothing stops the clasp releasing, and keep the tag light. You should be able to fit two fingers under the collar. See should my cat wear a collar?

• Look at the split ring. If it's bent, thinning or starting to open, replace it: they cost pennies, and a worn ring is the usual reason a tag falls off.
• Check the tag's hole isn't wearing through, and that any engraving is still readable. Tags wear a little on every walk: see why dog tags wear out.
• Check the collar's fit and the skin underneath. Our collar fit guide covers the two-finger check.
• After a bath, a swim or a muddy walk, check the tag is still there before the collar goes back on.

In a public place in the UK, a dog must wear a collar with the owner's name and address on it, or on a plate or badge attached to it (the Control of Dogs Order 1992). A harness on its own doesn't meet that, so a dog that walks on a harness still needs a collar and tag, and a microchip doesn't count either. Our UK dog tag law guide has the detail, and the dog tag wording maker lays out what to put on the tag.

A PetTag hangs from a ring like any other tag, so fit it with a split ring on the collar's D-ring, alongside an engraved tag or collar plate with your name and address. Anyone who finds your pet can then scan it with a phone camera to reach you straight away. See the tags.