Can Any Body explain the algorithm of Critical Path Method (CPM) use in Construction management?

1. A list of all activities required to complete the project (typically categorized within a work breakdown structure) ,
2. The time (duration) that each activity will take to complete,
3. The dependencies between the activities and,
4. Logical end points such as milestones or deliverable items.

FLOAT ACTIVITIES in Construction schedule where management considered a float activity which can be started earlier or at the end of the Construction period.