If you've decided you want to fence in your yard, there are a lot of factors to consider. First of all, what is the purpose of your fence? Do you want it for increased security, or simply for privacy? Do you want to keep children or animals contained? Or perhaps you simply like the look of fencing and want it for decorative purposes. You'll want to choose the material and style of your fence primarily in terms of its purpose, though both initial cost and maintenance will need to be taken into consideration. Wooden fencing is one of the lower-cost options, though it needs yearly maintenance and will have to be replaced after about 20 years. A picket fence is classic, and serves as both decoration and to contain children. Small animals may worm their way through it, and larger animals might need stronger materials. A picket fence will provide only partial privacy and not much security. Wood can also be used for high, solid fences which do serve for privacy and security and will contain animals.
Chain link fencing is less expensive and will last about 30 years with little to no maintenance. It can provide containment and security, but it is not very attractive. Unless it is woven with vinyl, it doesn't provide much privacy.
Vinyl and aluminum fencing are more expensive, but last a lifetime with no more than an annual washing. PVC vinyl fencing comes in many styles, from picket to full privacy. Aluminum fencing is an alternative to the more expensive wrought iron. Both are primarily used for decorative purposes, although they can be designed to provide security and containment as well.