DA is the product of GPS. In the old days, we had MDA - tho shall not descend below which was for nonprecision approaches and we had DH which was for precision/ILS approaches which meant we made a decision at that altitude and started the transition to missed approach or continue to a landing. It was understood that some additonal altitude would be lost in the transition to a climb. Approaches were built with this in mind.
Now move to the 90s and later. The upstart GPS approaches muddle things a bit. GPS is considered a nonprecision approach although a very precise one. For that reason, those approaches that are surveyed and meet certain criteria have a designated "Decision Altitude". This is the GPS/non precision approach stopping point to treat with similar definition as Decision Height. Be careful. Not all GPS approaches have "DA"s some will have "MDA"s. DA minimums are not dive and drive minimums, they are for stabilized VPATH approaches.
Mike