The simplest form of computer database is the flat file database. Microsoft Excel can be used, and is used, by many people as a database. But this flat file database has serious limitations. One is its slow speed. Another is that a flat file duplicates a lot of the data that could be entered just once (like having to type in, and spell correctly each time, Massachusetts for many customers). Duplicate data has to be input again and again. It also has to be sorted by the computer program. Slow sorting is the major cause of your mouse pointer turning into an hourglass (while you go for a break).

On the other hand is the state of the art type of computer database, the "relational" database. Although the user doesn't know how it's storing information internally, it is stored in a very efficient manner and operates very quickly when properly designed. Microsoft Access is a relational database. Duplication of data can be reduced to an absolute minimum (don’t type in Massachusetts every time, just click on MA!).