Clipping wings is necessary for all of the more social birds that are out of the cage. Birds such as canaries and other finches that stay in the cage don't need their wings clipped. Birds have been known to fly into windows, into pots of boiling water or other food, into ceiling fans, etc. We need to take the responsibility to protect them and this responsibility includes clipping wings.
Watch your veterinarian or bird groomer trim the wings the first time. A proper trim allows the bird to exercise its muscles and to coast to a landing if needed. It should prevent the bird from attaining additional altitude.
One person should restrain the bird wrapped in a towel. The wing should be extended. Using sharp scissors, remove the ends of the outer 6-7 feathers (these are the flight feathers). More of the feather can always be trimmed if needed. If a blood or pin feather is cut, it will bleed. This bleeding usually stops in a short amount of time. If the bird continues to pick at it and it continues to bleed, the feather can be plucked out.
Check the feathers on a monthly basis and trim as necessary. If the outer 2-3 feathers are left unclipped for looks, monitor closely as the bird may be able to fly.
If the bird does manage to escape to the outside world and fly off, immediately put his cage out in the yard with the door open and a big bowl of his favorite food in and on it. Hopefully, within a day or two, your feathered friend will decide the cage isn't so bad after all. Let people know you lost your bird. Put up fliers, call veterinary clinics and humane societies, and put an ad in the paper. Don't give up hope. Some birds are found and caught weeks after the escape. Keep up-to-date photos of the bird. Take pictures from both sides, front, and back. Write down the ID information whether it is from a leg band or a microchip. Having this information will help prove ownership if the need arises.