Chisel is a hardware construction language (DSL) embedded in Scala. It provides a rich set of abstractions (Module, Bundle, Reg, Mem, UInt, SInt, Bool, Vec, Clock, When) for describing synchronous digital circuits at the register-transfer level. The system compiles these circuit descriptions into an intermediate representation (FIRRTL/CIRRTL) and then uses the CIRCT compiler framework to generate synthesizable SystemVerilog. It also includes a comprehensive simulation framework (svsim, ChiselSim) for verification on Verilator or VCS, formal verification capabilities (LTL properties), and a standard library of reusable hardware components (counters, queues, FIFOs, arbiters, decoders, PRNGs). The architecture is a multi-stage compiler pipeline: user code elaboration, FIRRTL IR conversion, and CIRCT-based code generation. It relies on external tools like firtool, Verilator, Espresso, and Slang. The codebase is actively maintained with a clear versioning history (7.x), but carries significant technical debt from a deprecated FIRRTL package, an ongoing Scala 2 to Scala 3 migration, and a large surface of experimental features.