OpenAI Codex adapted GPT-style language modeling to public source code and introduced HumanEval as a way to measure whether generated functions actually passed tests rather than merely looked plausible.
GitHub Copilot placed large-model code generation directly in the editor, turning AI assistance from a separate research demo into suggestions delivered at the moment developers wrote software.
Under GitHub CEO Nat Friedman, the 2021 Copilot technical preview put Codex-powered whole-line and function generation into a mainstream developer platform and helped establish 'AI pair programmer' as a product category.