On its blog, Tumblr says the Tumblr Button offers "complete control over how your content appears when shared on Tumblr."
While the appearance of the Tumblr Button is similar to the share buttons offered by other services, the functional scope is significantly more advanced.
The Tumblr Button documents showcase how publishers can integrate the new button into their platforms. In its most basic implementation, Tumblr users can share a link, sans pre-filled description to an article or website.
The button can be customized to share a link to an article with a pre-filled description, a specific pull quote (complete with attribution) and even specific paragraphs from an article page. Images and video embeds can also be customized to work as Image and Video post types within Tumblr. The buttons can even be configured to work in PHP, Ruby or JavaScript.