Why are there bugs on the earth?

here are bugs in software due to unclear or constantly changing requirements, software

complexity, programming errors, timelines, errors in bug tracking, communication gap,

documentation errors, deviation from standards etc.

• Unclear software requirements are due to miscommunication as to what the software should

or shouldn't do. In many occasions, the customer may not be completely clear as to how the

product should ultimately function. This is especially true when the software is a developed for

a completely new product. Such cases usually lead to a lot of misinterpretations from any or

both sides.

• Constantly changing software requirements cause a lot of confusion and pressure both on the

development and testing teams. Often, a new feature added or existing feature removed can

be linked to the other modules or components in the software. Overlooking such issues causes

bugs.

• Also, fixing a bug in one part/component of the software might arise another in a different or

same component. Lack of foresight in anticipating such issues can cause serious problems and

increase in bug count. This is one of the major issues because of which bugs occur since

developers are very often subject to pressure related to timelines; frequently changing

requirements, increase in the number of bugs etc.

• Designing and re-designing, UI interfaces, integration of modules, database management all

these add to the complexity of the software and the system as a whole.

• Fundamental problems with software design and architecture can cause problems in

programming. Developed software is prone to error as programmers can make mistakes too.

As a tester you can check for, data reference/declaration errors, control flow errors, parameter

errors, input/output errors etc.

• Rescheduling of resources, re-doing or discarding already completed work, changes in

hardware/software requirements can affect the software too. Assigning a new developer to the

project in midway can cause bugs. This is possible if proper coding standards have not been

followed, improper code documentation, ineffective knowledge transfer etc. Discarding a

portion of the existing code might just leave its trail behind in other parts of the software;

overlooking or not eliminating such code can cause bugs. Serious bugs can especially occur

with larger projects, as it gets tougher to identify the problem area.

• Programmers usually tend to rush as the deadline approaches closer. This is the time when

most of the bugs occur. It is possible that you will be able to spot bugs of all types and

severity.

• Complexity in keeping track of all the bugs can again cause bugs by itself. This gets harder

when a bug has a very complex life cycle i.e. when the number of times it has been closed, reopened,

not accepted, ignored etc goes on increasing.