This document provides a high-level overview of Ruby internals in 3 paragraphs or less: The document discusses key aspects of Ruby internals including the symbol table which implements a generic hash, values and identifiers represented as unsigned longs, builtin data types like Array and classes having instance variable tables and method tables. It also covers casting values, type flags, method inclusion via modules, string and array implementation with preallocation, blocks and frames representing method calls, threads scheduled via time slicing, and garbage collection which marks and sweeps objects across heaps. The author is Lourens Naudé, a Ruby contractor building a consumer forex platform. They provide open source contributions and a crash course on Ruby internals with