Tumblr was one of the most popular micro-blogs before the explosion of the social media arena. However, it went through a period of decline a few years ago, and was taken over by Automattic – the owner of WordPress.
Recently, Automattic announced they will be switching Tumblr to use WordPress technology to power it. This will be done in the background, where the user may not be aware of the change.
For Automattic's own part, this step is expected to further facilitate the maintenance and introduction of various new functions on Tumblr. It will also allow WordPress.com's already optimized infrastructure with multiple large investments to be used in using Tumblr.
Automattic says this transfer process may be one of the largest in the history of the internet. Tumblr today has over half a billion blogs, and this technical migration process is expected to take some time.