> For the complete documentation index, see [llms.txt](https://albertlidesign.gitbook.io/alfe/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://albertlidesign.gitbook.io/alfe/user-guide/overview.md).

# Overview

This section provides an overview of ALFE. We describe its design as well as the capabilities provided by the library. ALFE is organized into different modules. At the core of the library is the FEsystem module providing a data structure for polygonal surface meshes. On top of the FEsystem module the Element module provides implementations of various finite element types such as triangles, pixels, quadrilaterals, tetrahedrons, hexahedrons and voxels. The optional TopOpt module provides topology optimization tools based on Bi-directional Evolutionary Structural Optimization.