A strip footing is any continuous footing underneath a foundation wall, commonly found around the perimeter of a building, and is one of the most commonly used foundations of them all. A strip footing is usually reinforced, both horizontally and vertically. A mechanical key is cast into the bottom of the footing to help prevent the foundation wall above from slipping off the footing.
When the grade changes along the length of a strip footing, often it will be designed as a Stepped Footing, where it drops or rises to match the grade. Stepped footings are much more economical than a constant level strip footing.