What's your PotentialMulti-Site ROI?
The ForresterWave™: Web ContentManagement Systems,Q1 2015
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Facebook uses a meta tag called Open graph meta tags (e.G. For
facebook sharing) You can actually use a module which allows you to
select an image per post. https://drupal.org/pr
Otherwise you could set the meta tag in your themes header?
More information about text formats