The Trilinos Project is an effort to develop algorithms and enabling technologies within an object-oriented software framework for the solution of large-scale, complex multi-physics engineering and scientific problems. A unique design feature of Trilinos is its focus on packages.
For help with a particular package, see the website and accompanying documentation for that package. Links to these can be found down the right side of any page on the website and at the package website.
Trilinos is licensed on a per-package basis. Most packages are now under a BSD license, some are published under the (L)GPL. Details can be taken from the documentation of each package.
Pull requests MUST be submitted against the develop branch. The branch you see on the main page is the master branch. If you accidentally make your pull request against the master branch, you can switch it to be against the develop branch, by following these instructions: https://github.com/blog/2224-change-the-base-branch-of-a-pull-request