TOPIC: Free Float vs. Total Float vs. Project Float

Hi

I am struggling to understand the concept of 'float'. Need help understanding the difference between FREE FLOAT, TOTAL FLOAT and PROJECT FLOAT and how each of them is calculated.

I possess the very basic notion on float--

1) Float is the amount of time an activity can be delayed without delaying the start of the immediately following activity.

Float= Late Start (LS) - Early Start (ES)

OR

Float= Late Finish (LF) - Early Finish (EF)

2) Critical Path has zero float