Outdoor cat runs, hedging and fencing
Enclosing your garden, or parts of it, will allow your cat to experience the outside world without any dangers
If you want your cat to experience the outside world, but don't want the risks of your cat getting lost, hit by a traffic, stolen, or seriously injured, then enclosing your garden or creating a run might be a good option.
Growing tall hedges can help keep your cat in your garden, although you need to look at all possible exits and hedging might only be part of the solution. If the hedging has an open structure, cats will easily climb up it and may even use it as a useful tool to aid their exit from you garden. If you go for a hedge which has densly packed leaves and numerous small prickly branches then your cat is less likely to use it and it will make a good natural barrier.
Not to be confused with electric perimeters which deliver a warning shock or sound to your cat if they come close, an electric fence is a wire fence, or series of wires, set around your garden and connected to a battery. Anything which comes into contact with the fence gets quite a shock. These are a rather severe form of boundary enforcement and the risk of getting intensities wrong (some are designed for horses) makes them unsuitable for use with small animals like cats.
This fence has a spring loaded overhang which cats cannot climb
Cat proof fencing
There are a number of companies which specialise in cat fencing. The basic idea is to use a tall fence surrounding the garden which angles inwards at the top. The inward angling is what stops the cats from climbing over the top. In almost all cases this stops cats from leaving the garden, although there are always determined cats who can figure out a way over the fence. It is important to use fencing designed for this purpose as other types may cause damage to cats claws should they become stuck.
A novel invention which works well if used around the entire perimeter is to use cat 'rollers' which attach to the top of a fence. Once the cat climbs the fence and gets to the rollers, any attempt to get a grip results in the rollers just spinning, and so the cat gives up and goes back down. Eventually the cat will not bother and just stay in the garden. Rollers can be a more attractive looking solution than tall mesh fences, which look a little prison-like.
A run is basically an enclosed area, normally a large wooden-framed cage which connects via a door or cat-flap to the house. You can purchase runs but since every house is different it is often more practical to build one yourself or hire a local handyman to do the job. A run can be as big as you like, the bigger the better and should contain climbing areas, shelters, and dug areas for toileting in.
Runs offer complete safety from other animals (or humans) and your cat can come and go as it pleases via a cat-flap. Of course a run is not as much fun as the real outside world but it will at least allow your cat to view interesting things like birds, eat grass (which helps digestion) and toilet naturally.
If you opt for a form of cat fencing or deterrent you should make sure that your cat has a route back in, should it defeat its imposed boundaries. A cat fence should only work one way so that if your cat does get out, it can get back in easily. One problem with such fencing is that should a neighbors cat, or even a wild animal get into your garden, it may not be able to get out. This is why sheltered areas for your cat are important, so that is can hide and is not forced to share an open space with another animal which may be distressed and unpredictable.