You can call pergolas arbors or gazebos but any shade-creating structure that doesn't have a solid roof fits the bill. Many are used to train grape or other vines to create a leafy overhang during the summer months. Dressing up your backyard with a beautiful arbor or pergola is an inexpensive way to create outdoor living space and add a touch of style.
The basic structure
Essentially a pergola is nothing more than two to four uprights with a very open lattice of lumber across the top. If you build yours next to another structure like your house or even a raised deck, you might only need two upright posts as the other end of the lattice work will be supported by the structure. However, most pergolas are free standing and use four upright posts to create a square or rectangular area of shade. It is up to you whether your shady area is on a patio or a deck or just a casual seating area finished with gravel or dry-set flagstone. In addition, how the lattice boards are cut--plain or fancy--is your choice and should fit in with any existing decoration.
Controlling the shade
You can also control the amount of shade by using more or less wood in your lattice work across the top. Of course, if you're going to train a deciduous vine you'll have more shade in the hot summer when the leaves are on it. Isn't that just what you wanted? Maybe, but if you don't like the look of dormant vines all winter, you might just have a structure with no vines on it. Another option is to use hanging plants to create additional shade when you want it and to bring them inside during the winter or put them away if they are annuals that die.
Do it now
Spring is a great time to get started on dressing up your back yard with a new pergola. The ground is soft from the rains so the digging is easier, and it's not super hot yet. Plus, you have time to get some new plants and landscaping put in around it so it will be beautiful this summer.
Do it yourself?
There are lots of plans on the Internet and in books at most home improvement stores. If you can dig a post-hole, set a post in concrete and cut and nail boards together according to a plan, you can probably build your own pergola.
You can also check out the many Atlanta-area qualified landscapers if you want to hire someone. Your costs will vary depending the type of wood you use (cedar is costlier than pressure-treated pine), the size of your pergola and how much decorative cutting you want done.