What is block hour in ACMI lease? What is difference between Block hour and Flight Hour?

In ACMI Lease of aircraft, prices are calculated based on block hours. What is a block hour and how are they calculated?

Can any one show me an example for a flight like this...


Delay at Runway (takeoff): 20 Minutes
Flight Time: 1 Hour and 40 Minutes


Then what could be block hours? 2 Hours or 1 Hour and 40 Minutes?
Block time starts when the aircraft is pushed back from the gate, and ends when it arrives at the corresponding gate.

It is the total time the aircraft is in use, typically only calculated for revenue movements.

Imagine a flight:


Pushback 1000
Taxi 1030
Takeoff 1035
Touchdown at destination airport 1445
Taxi to gate 1500


Total block time is 5 hours