What are the advantages of using leads?

Using leads allows your company to maintain two separate lists - one for prospective customers and one for existing customers. You can store your prospects as leads, and then when a lead becomes qualified, you can convert it to an account, contact, and, optionally, an opportunity.

Leads are especially useful if your company has two separate teams - one that handles lead generation and mass marketing and one that handles sales. The lead generation team can concentrate their work on the Leads tab, and the opportunity team can use the Account, Contact, and Opportunity tabs.