Data file needs to be cleaned regularly to eliminate errors, duplication and outdated information. If incorrect entries are made, customers drop off, people change jobs or leave, and companies merge or go out of business. Lists of names, addresses, contacts, and contact history, etc. needs to be reviewed and corrected if you want your database to work efficiently. Rick Cook (writes articles on computers and related technology), writes in his article about how to clean data file. Read more at: http://it.toolbox.com/blogs/insidecrm/crm-clean-your-data-70375