umbraco Pro is our central product, which is a certfied version of umbraco with guaranteed support and upgrade service. Support is provided by members of the core team with experience from hundreds of umbraco implementations.
For DIY'ers, there's also a free version available. The umbraco framework is open source (free software) under the MIT license and the user-friendly UI bundle is freeware with full source code available.
For more information about umbraco in general, take the tour, download and install in the morning, follow the guides and samples and be up and running by the afternoon.
As a supplement to umbraco and to finance development, we - the umbraco company - offer additional products and services. These products are not necessary to use umbraco - even for professional use - but in many cases they can be very handy and huge timesavers: