The main aim of software testing is to find software bugs as soon as possible and debug the software. Software bug is a mistake or fault in a computer program that stops the software from executing its projected function. These bugs arise due to the mistakes in source code or design of the software program. Source code is a set of files that converts the form of human readable data in to computer- programming language. A report is made depicting the details of the bugs present in the software. If there are numerous bugs in a program then it is called buggy. It is really important to check out and correct these bugs before the launch of the software since once activated in the user computer, they infect the programming of the whole system.