Autofac is a mature, production-grade Inversion of Control (IoC) container for .NET, providing dependency injection (DI) capabilities. The core library manages object lifetimes, service resolution, and dependency graphs through a fluent registration API and a pipeline-based resolution engine. It supports a wide range of features including constructor and property injection, decorators, open generics, assembly scanning, metadata, keyed services, and advanced lifetime scopes (singleton, per-scope, per-dependency, per-owned). The architecture is built around extensible middleware phases (scope selection, decoration, sharing, activation) and registration sources that dynamically provide services. Autofac is designed for high performance and AOT/trimming compatibility, with extensive benchmarks and a dedicated AOT verification workflow. It is a library, not an application; it is consumed by other .NET projects to manage their dependency injection needs.