Definition
Testing whether the system is compatible with other systems with which it should communicate.
[Source: BCS]
Comment
Compatibility testing is essentially a superset of configuration testing, interface testing and integration testing.
It refers to any kind of compatibility between systems or between systems and their environments (such as web-sites and browsers, applications and operating systems). Always check the scope of compatibility testing.


On many programmes and large projects, testing will take up a significant portion of the budget. But it will receive less management attention than an activity of this size warrants.