Perhaps the most social form of blogging, this platform encourages followers to reblog posts, quotes, photos, animated GIFs and video to reach a larger audience than their own group of followers. Original works encourage new followers to join your network and when reblogging you can obviously add your comments and 2 cents.
Tumblr supports using your own top level domain name (ie: jeanmonroe.com) free, so developing a Tumblr blog into a full fledged professional profile or business website is extremely do-able.
Tumblr is owned by Yahoo, now. This means that they now will share all your data with the NSA and use it to spy on your digital life and history should they want to (the expansion of the NSA's data centers fervent growth is the most corrupt government spending spree known to all of world history).
Yahoo seems to be on the path of enabling full-fledged e-commerce operations through the platform, as well.