Meaning of battery Stand by time and Usage time - difference

What is the difference between phone's battery stand by time and usage time ?

The difference between battery stand-by time and usage time is essential, because each of them is focused on different usage of phone or other device.

Stand-by time is the longest time that a battery will last, when the phone is connected to the GSM network, but is not in active use.

Usage time is the time that a battery will last, when the phone is being is connected to the GSM network and is used in a regular average way.

To evaluate the lasting of battery, there is also the Talk time used. Talk time is the longest time that a battery will last, when the phone is connected to the GSM network and you are constantly talking (having a phone call).

Stand-by time and Talk time are often used for a phone battery comparison.