This document discusses how to use FEBio and describes the input file format in detail. Chapter 2↓ describes how to run FEBio and explains the various command line options. It also discusses the different files that are required and created by FEBio. Chapter 3↓ describes the format of the FEBio input file. An XML-based format is used, organizing the data in a convenient hierarchical structure. Chapter 4↓ gives a detailed overview of the available constitutive models. Chapter 5↓ discusses the restart capabilities of FEBio. The restart feature allows the user to interrupt a run and continue it at a later time, optionally making changes to the problem data. Chapter 6↓ describes the multi-step analysis feature, which allows the user to split up the entire analysis into several steps. Chapter 7↓ explains how to setup and run a parameter optimization problem using FEBio's optimization module. Chapter 8↓ provides helpful information for troubleshooting an FEBio model and offers guidelines that help users avoid common problems.

Although this document describes some of the theoretical aspects of FEBio, a complete theoretical development can be found in the FEBio Theory Manual$.$ Developers who are interested in modifying or extending the FEBio code will find the FEBio Developer's Manual [A]  [A] The developers manual is only available online (see https://febio.org for more information) very useful.