he Community Tech Tree is a mod designed to extend the stock technology tree to accommodate many community mods in an inclusive and extensible manner. This takes the form of expansions to the current tech tree. It provides new and extended branches for command pods, thermal management, ion engines, nuclear power and propulsion, and many more useful nodes.
You can check out the layout and added nodes on Gliffy, though it's not always perfectly up to date.
You'll need to install ModuleManager version 2.6.2 or higher, if you don't already have it, in order to extend the tree.
The Community Tech Tree will not assign parts to mods itself, instead, it is up to mods to support it themselves. Any mod that does not support the CTT will still work just fine, it will just not take advantage of new tech nodes that are added.
If a mod you like doesn't support the tree, let the author know, or produce your own patch to add support. The best way to to do this is via ModuleManager patches. Simply create an empty .cfg file to be packaged with your mod (call it anything you like, I use ModNameCommunityTechTree.cfg), and include entries as follows:
@PART[panel-static01]:NEEDS[CommunityTechTree] { @TechRequired = advSolarTech }
This assigns the part "panel-static01" to the Advanced Solar Tech (advSolarTech) node, and will only run in the presence of the Community Tech Tree. A list of new nodes and additional details can be found in ForModders.txt, which is included in the download.
If you are a modder, you can link to this little icon if your mod supports or bundles the CTT: