The concept of memory leakage is related to allocation of 
dynamic memory in the code.  Whenever the dynamic memory is 
used in the code for ex. in a function and the memory is 
not released, one is going to get the error message 
say "memory not available" if the function is called again 
and again.  Though the code is syntactically and logically 
correct, one is going to receive the error message if the 
dynamic memory is used (using new command in 'C' 
Programming language, we can allocate dynamic memory) but 
not released.

Certain Tools like Bounce Checker can be used to check the 
memory leakages.