CPM is a deterministic project scheduling algorithm that identifies the critical path - the longest sequence of dependent activities determining minimum project duration. Activities on the critical path have zero total float (slack), meaning any delay directly impacts project completion. CPM calculates: forward pass (earliest start/finish times), backward pass (latest start/finish times), and float (total, free, and independent). The method supports: crashing (reducing activity durations), resource leveling, and schedule optimization. CPM is widely used in construction, manufacturing, and software development projects.