A patio awning will generally consist of a large panel of fabric which is attached to and wrapped around a roller tube at the top, and this fabric extends and is attached to the front rail of the blind.
The front rail is bolted to a pair of folding arms and the back of these are fixed at the awning body, which is itself installed to the building.
The folding arms are articulated, and have two tensioned springs inside each, which are attached via cables, belts or chains around the elbow of the arm. It’s these arms that provide sufficient tension to the enable the fabric to keep flat between the front rail and roller.
A gearbox with removable handle, or an integral tubular motor allows the awning to be extended or retracted to the desired position.
One critical consideration - the projection of the awning is how far the thing will project away from the fixing and you'll need to understand how the time of day and year, as well as your building's orientation will affect just how much shade the awning will offer. Ensure you ask your dealer to show you how the awnings effects will change over the time of year and day!
Other types of awning area available - drop arm awnings, slide arm awnings, as well as Dutch Canopy blinds - these are dealt with elsewhere - look for our Guide to Dutch Canopies.