Testing is the process to check the changes in code or data to make sure it meets the business requirements.  It is the step before moving changes into the production environment.  It is probably the most important step in the project life cycle.  If you test properly you can detect problems with the code before they become catastrophic issues in production.

Today I read a comic strip that had to do with testing in IT.  In the strip the main character is upset that the test cases they just completed, didn’t have any relevance to the real world.  He was lamenting the fact that he had just spent two weeks testing something that was meaningless.  The manager in the comic strip said that they would use the test results anyway because it is the only data they have.  At that, the main character says something unkind and leaves.  The boss asks why he is so cranky and another character says it has something to do with data.  Unfortunately, this comic strip reflects reality.  There are times when the testing being done for a project, doesn’t bear any relevance to the real world.

That is the age old data integration question, "How current should the data in your Development environment be?" There are several factors to consider when answering this question.