A decision is a final product of a specific mental/cognitive process by an individual or group, which is called decision making, or in more detail, Inactive decision making, Reactive decision making, and Proactive decision making. Therefore it is a subjective concept. It is a mental object and can be an opinion, a rule or a task for execution/application.
More precisely speaking, a mental object D is a decision if obtained by a conscious choice of only one opinion or one action (from a known set called alternatives), and it is designated for an application.
Decisions, at times, are influenced by factors that have almost nothing to do with surrounding reality or material facts. For example superstition may play a significant role in decision making, and so are other beliefs such as numerology, astrology, and many other forms of similar unscientific and perhaps even spiritual standards. Decisions can also be made by AI computer programs and autonomous robots. That what essentially influence a decision is the set of alternatives available for a decision-maker and choice criteria applied. These are often addressed using decision support systems
In different human activity domains, decision has many local meanings, for example,