Core is Jane Street's alternative to the OCaml standard library. The need for an alternative to the standard library is clear: OCaml's standard library is well implemented, but it's narrow in scope, and somewhat idiosyncratic in its interfaces. Core's origin's date back 10 years, to the first uses of OCaml at Jane Street. Today, Core is at the base of the multi-million-line OCaml codebase at Jane Street, which is actively used by on the order of a hundred people at Jane Street for their daily work. The talk will provide a brief overview of the design principles behind core, including our approaches to: - building consistent and interoperable interfaces - error handling - naming - organization of types, values and and modules We'll also discuss the the internal and community process surrounding Core, including how contributions from external providers are handled, and how our own internal Q/A process works.