check points are nothing but a verification point we can 
verify the properties of object,bitmap,database using the 
checkpoints ,this is nothing but a user_interface testing
In qtp to verify the componets it supports 7 types of 
checkpoints
1.standard checkpiont
2.text checkpoint
3.textarea checkpoint
4.bitmap checkpoint
5.database checkpoint
6.accessibility checkpoint
7.xml checkpoint

"checkpoint is a feture provided by qtp which is used for 
checking something  during executiion at any of time".
checkpoints  works in 2 phases:
1.pre-execution phase
2.while execution phase
types of checkpoints:
1.standard checkpoints
2.bitmap checkpoints
3.text checkpoints
4.textarea checkpoints
5.database checkpoints
6.xml checkpoints
7.page checkpoints
8.table checkpoints
9.image checkpoints
10.accessability checkpoints
7,8,9 are hidden checkpoints.
7-10 are web related checkpoints.