Lead generation is a part of advertising and can include non paid sources should as referrals from existing customers or repeat customers or even organic search engine results.
Lead generation can derive from different sources such as through referrals or pay per click advertising, other types of advertisements, customer service calls/cold calls and through direct search engine traffic. The three most popular types of online lead generation are through the use of web referrals, search engines and direct traffic. Once the new lead is generated it is managed internally to maximize potential.
An example of this is if a user enters their email address on the website and concludes an order or other event. After that the user will be marketed to directly from the site to their email and potentially from other related businesses. Users have a choice on most sites as to whether they are willing to share their email with third parties for the purpose of advertising.