RDF is a whole separate topic, but one thing that derived from RDF is very central to blogging and Tumblr: RSS
RSS stands for RDF Site Summary, or more commonly known as Really Simple Syndication. It is a format that represents content available from a website, typically of a serial variety.
Everything in Tumblr is designed to make blogging quick, easy, and yet powerful. It starts with the sign-up process, asking only what is really necessary.
The hardest part in sign-up might be finding a short URL. Tumblr has gotten popular and many URLs are taken.
Tumblr provides many of the basic features one might expect for creating a blog:
Tumblr’s simiplicity is nice, but the broad feature set is a key distinction.
Tumblr is a little more than just blogging. It provides feature overlap with a number of popular services.