Facebook's Graph API allows websites to draw information about more objects than simply people, including photos, events, and pages, and their relationships between each other. This expands the social graph concept to more than just relationships between individuals and instead applies it to virtual non-human objects between individuals, as well.

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You probably noticed that some links on Facebook and Twitter looks better than others. They have relevant title and description and most of them have a nice image linked. This is not a coincidence or dark magic and you can implement it for your website in couple minutes.