Sometimes you'll be looking for general faults, and trying to crash the systems. Or you'll know a fault exists, and you'll be trying to isolate the cause of it. New faults in software are often found by both developers and users alike. Isolating and fixing the faults, alas, always falls to the developer. If you're lucky, you'll have a fairly good idea of where the problem lies.
Bugs can be present in all phases of the software development life cycle.
In ad hoc software development, we often know that our software has bugs, but we don't know exactly what they are. As the number of features in software increases, programs become more complex to construct. This increases the likelihood of introducing bugs and makes it harder to detect them. Many bugs only present themselves after certain combinations of code are executed. Detecting Bugs Detecting bugs is a fairly simple task during the early stages of software development.