Many people often forget to set the Customization Prefix when they customize CRM. When you create new entities and attributes CRM automatically creates tables and columns for you in its SQL Server database. It adds the Prefix to the names of those tables and attributes. CRM’s Web Services and underlying platform also uses these ‘schema names’ when referring to entities and attributes. The Prefix is designed to ensure a level of uniqueness amongst customizations and to help System Administrators understand the source of a customization. I highly recommend that all customers and partners set the Prefix of their CRM systems to something unique (like an abbreviation of their company name).
To set the prefix simple navigation to Settings > Organization Settings > System Settings. Then in the customization tab there is a single text box allowing you to set the Prefix.
Program Manager, Customization