Float in Project Management is the amount of time that an activity can be delayed from its Early Start date without affecting the finish date for all other activities that follow such activity. Float occurs only for activities that are not on the Critical path.
Total float is a type of float where the total amount of an activity required can be delayed without delaying the project finish date.
Total float will help you to know the date that an activity can start without affecting the end date for the overall project,
This is the amount of time an activity can be delayed without delaying the earliest start of any activity that immediately follows it. Free float unlike Total float is always calculated by subtracting the Earliest finish of an activity from the Earliest start of its successor activity.