A revenue stream is a source of revenue for a company or an organization. The revenue model determines the types and sources of revenue that companies or businesses generate. Revenue types include product sales, service fees, advertising sales, data access fees, license fees, or even commissions. Ad-based revenue models entail creating ads for a specific website, service, app, or other product, and placing them on strategic, high-traffic channels. The subscription revenue model entails offering your customers a product or service that customers can pay for over a longer period of time, usually month to month, or even year to year.