The world's biggest retailer is expanding its ad business this year, according to MIT Technology Review. Amazon has developed an in-house platform for targeting ads to people who have visited its site, and will likely open these ad services more widely in 2013. This will enable other companies to capitalize on what the online retail giant knows about consumers' purchase habits and deliver ads to highly-targeted audiences.

This platform is a game changer for the retargeted advertising market. It's an exciting additional option for advertisers, allowing them to direct ads to consumers based on purchase history rather than just search habits or interests. The added dimension of buying behaviour provides a significant targeting parameter that marketers will be eager to incorporate into their retargeting campaigns.

Read the full article on MIT Technology Review's website.