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.

Each Trilinos package is a self-contained, independent piece of software with its own set of requirements, its own development team and group of users. Because of this, Trilinos itself is designed to respect the autonomy of packages. Trilinos offers a variety of ways for a particular package to interact with other Trilinos packages. It also offers a set of tools that can assist package developers with builds across multiple platforms, generating documentation and regression testing across a set of target platforms. At the same time, what a package must do to be called a Trilinos package is minimal, and varies with each package.

Trilinos provides capabilities in meshing, load balancing, discretizations, mathematical optimization and uncertainty quantification, and transient, nonlinear & linear solvers. Trilinos software is designed for scalability on the largest computer systems available and represents the state-of-the-art in scalable unstructured linear algebra, scalable unstructured preconditioning, block iterative methods, embedded optimization, stochastic methods, compatible discretizations and parallel partitioning algorithms. Use of object-oriented programming techniques makes Trilinos highly extensible, including the ability to adapt readily in both algorithms and implementation to radically different machine architectures.