Isolated footings (also known as Pad or Spread footings) are commonly used for shallow foundations in order to carry and spread concentrated loads, caused for example by columns or pillars. Isolated footings can consist either of reinforced or non-reinforced material. For the non-reinforced footing however, the height of the footing has to be bigger in order to provide the necessary spreading of load.
Isolated footings should only be used when it is absolutely certain, that no varying settlements will occur under the entire building. Spread footings are unsuitable for the bearing of widespread loads. In this case, either strip (continuous) footings or mat footings are used.
The basic program for design and analysis of isolated footings is GEO5 Spread Footing. It is able to design the entire footing and to compute settlement, rotation and bearing capacity of the footing. Also, it determines the required longitudinal and shear reinforcement (punching).
Further sources:
Engineering Manual - Settlement of a spread footing
Online Help - Program Spread Footing
Video Tutorial - Introduction to Spread Footing