The A-Series and B-Series (by J.M.E. McTaggart)

J.M.E. McTaggart's A-Series and B-Series describe two ways of understanding time. The B-Series treats time as a fixed order of events—past, present, and future—like a timeline where events are static, simply ordered. The A-Series adds a dynamic aspect, emphasizing the flow of time: events move from future to present to past. Think of the B-Series as a snapshot of events' positions, while the A-Series captures the experience of time passing. McTaggart argued that both series are essential, but the true nature of time involves the ongoing change described by the A-Series.