Stress testing tries to break the system under test by 
overwhelming its resources or by taking resources away from 
it.

Stress testing - Stress testing is subjecting a system to 
an unreasonable load while denying it the resources (e.g., 
RAM, disc, mips, interrupts) needed to process that load. 
The idea is to stress a system to the breaking point in 
order to find bugs that will make that break potentially 
harmful. The system is not expected to process the overload 
without adequate resources, but to behave (e.g., fail) in a 
decent manner (e.g., not corrupting or losing data). The 
load (incoming transaction stream) in stress testing is 
often deliberately distorted so as to force the system into 
resource depletion. 

Stress Testing : to check the performance of an application
based on increasing no.of resources.

Stress test: by increasing the load, at what point of load 
the application would fail to perform.

Stress testing is subjecting a system to an unreasonable
load while denying it the resources (e.g., RAM, disc, mips,
interrupts, etc.) needed to process that load.  The idea is
to stress a system to the breaking point in order to find
bugs that will make that break  potentially harmful.  The
system is not expected to process the overload without
adequate resources, but to behave (e.g., fail) in a decent
manner (e.g., not corrupting or losing data).  Bugs and
failure modes discovered under stress testing may or  may
not be repaired depending on the application, the failure
mode, consequences, etc. The load (incoming transaction
stream) in stress testing is often deliberately distorted so
as to force the system into resource depletion.

stress testing:
              stress is defined as the ant of resisting 
force offered by the body when it is subjected to a force 
per unit area.
            so by testing the specimen under this 
conditions one can know the load or amount of that a body 
can withstand. by knowing the point at which the specimen 
fails we can apply laod below that load.