Retargeting
Retargeting is one of the coolest and newest ways to really benefit from the huge audience that the internet offers.
Retargeting is the option to show your ads to website users who have previously visited a specific site or type of site that you specify. For example:
You are a grocery store wishing to target anyone who has been to the directory site, grocerystores.com.
Suzy Smith goes to www.grocerystores.com
Suzy then goes to Comcast.net to read her email.
Your ads are shown to Suzy while she is reading her email because you know that she has been to www.grocerystores.com. If Suzy had not visited www.grocerystores.com previously, then your ads would not be shown to her.
Other online advertising methods are Pay Per Click, Contextual Advertising, and Banner Advertising.