The social network embeds a widget in tweets that shows users what is being linked to on those sites.
Twitter is now giving its users a preview of content from Amazon and iTunes whenever a person tweets a link to something on those sites. The product listing appears automatically below the tweet, above the usual information you get when you click on a tweet like replies, retweets and Twitter users mentioned. This is an extension of its existing preview feature, which works with sites like YouTube and Twitpic.
For Amazon, it shows a picture of the product with the main details and most helpful customer reviews. There is also a ‘Learn more or buy’ button for you to click through to the main site. For iTunes apps it lists the main details along with screenshots. This embedded widget is a way for the site to monetize while offering its users a useful feature.