OODA stands for:
Colonel John Boyd, Military Strategist, created this model once he considered decision making for military strategy happened in recurring loops. The idea is that when moving to action you first observe the battlefield or what ever area you are operating in. Once you have done this you then look at that information in terms of context or Orientation. You may think of this as shaping a mental model and then continual deconstructing and reconstructing this information based upon all new observations and the orientation that is created. The idea is that this is not a static model and rather than simply a linear formula you should be thinking of it as many ongoing loops. I like to think of it a bit like Edward de Bono’s Six Thinking Hats. In which you are trying to get perspective from different vantage points. Boyd considers this central to the model because based on how you observe you will sort, evaluate and decide based on your orientation. (See Attribution Error) Once you have formed your most accurate orientation you move to consider alternative decisions and choose one. Once chosen you move to Act. Once acting you take the feedback via observation and you keep re-examining that decision.
Boyd saw this as a group of interacting loops that are in continuous operation until the end of the battle. He also believed that the level of energy in each loop depended on which phase you were in during the combat.