# Explanation

Explanation is **understanding-oriented**: it illuminates the *why* behind ReSim's design. Read these articles when you want to build a mental model, not when you need step-by-step instructions.

## Articles

- [Understanding Batches & Tests](../guides/batches-and-tests.md) — how ReSim structures test runs, what a batch is, and how individual tests relate to it

## ReSim U

ReSim U is a collection of deeper technical articles on the mathematics underlying autonomous systems:

- [Introduction to ReSim U](../resimu/introduction.md)
- [Lie Group Dynamics](../resimu/lie_group_dynamics.md)
- [Dual Quaternions for SE(3)](../resimu/dual_quaternions_for_se3.md)

More explanation articles are coming, covering topics like the ReSim testing model, the metrics pipeline, and how to design good test experiences.