On my view there are three modes of possibility: logical, metaphysical, and actual. Logical possibilities are those permitted by logic, metaphysical possibilities are those permitted by logic and the laws of metaphysics, and actual possibilities are those permitted by logic, the laws of metaphysics, and actuality.
When mere metaphysical possibility is too broad to be relevant, and actual possibility is too narrow, we turn to “real” possibilities to describe possible worlds in which the basic properties of the actual world obtain and in which history has gone identically to the actual world up to a given point.
A moment of reflection should yield the observation that there are alternate real possibilities, that is to say that for a typical given moment in time, there is more than one possible world which shares a history with the actual world up to that moment.
The view that such alternate possibilities exist has the mind-blowing implication that free will is possible. This is because an agent may be the one who supplies the final conditions necessary to actualize one of these real possible worlds. Imagine that there are two possible worlds that share a common history up to a given point in time (there are two “real possibilities”), and the only difference between them at this given time is the decision of a given person. From there, the two worlds will no doubt diverge in more than one regard. In such cases it is up to a person to choose which possible world is the actual world. Naturally life is a bit more complicated, as there are billions of agents making billions of decisions, some of which are more heavily influenced by their antecedent conditions than others. But in this way, we are all freely co-creating the actual world by choosing between real possibilities.