Page "Software bug" Paragraph 11

In software development projects, a " mistake " or " fault " can be committed at any stage during development.

Bugs are a consequence of the nature of human factors in the programming task.

They arise from oversights or mutual misunderstandings made by a software team during specification, design, coding, data entry and documentation.

For example, in creating a relatively simple program to sort a list of words into alphabetical order, one's design might fail to consider what should happen when a word contains a hyphen.

Perhaps, when converting the abstract design into the chosen programming language, one might inadvertently create an off-by-one error and fail to sort the last word in the list.

Finally, when typing the resulting program into the computer, one might accidentally type a "<" where a ">" was intended, perhaps resulting in the words being sorted into reverse alphabetical order.

More complex bugs can arise from unintended interactions between different parts of a computer program.

This frequently occurs because computer programs can be complex — millions of lines long in some cases — often having been programmed by many people over a great length of time, so that programmers are unable to mentally track every possible way in which parts can interact.

Another category of bug called a race condition.