This document provides an overview of LLDB, an open-source debugger developed by Apple. It discusses LLDB's architecture, how it uses Clang and is scriptable/pluggable. It also summarizes how LLDB sets breakpoints, evaluates expressions by running on the target process, and prints structured variables using Clang type representations. Testing for LLDB consists of around 20 test cases written in Python. There is opportunity for external contributors to help with areas like testing and improving the CLI.