Why is quality of Data important?

There is a saying in the database industry - GIGO. It stands for garbage in Garbage out. The point of a database is to maintain data in a way that it has a use. For example, in a business a database might be used for inventory. What good would it be if the database didn't contain the right information on quantity and price. Also when you sell something you would like to have its quantity decremented in the database. If this didn't happen reliably you have a big problem. There are other factors in data quality that might be associated with the precision of the data. For example you might have a piece of data stored as an integer, but find out later that you actual need floating point for more precision in your queries.