Visual Studio Code
Microsoft's free editor — launched 2015, built on Electron + TypeScript. Drove LSP, DAP forward and became the world's most-used code editor (Stack Overflow Developer Survey, 2021+).
The actually open project is "Code-OSS"; the code.visualstudio.com binaries are proprietary (Microsoft license, telemetry). VSCodium is an open-source rebuild without tracking. Web version on vscode.dev and GitHub Codespaces.
Forks that became their own products: Cursor (AI-first), Windsurf (Codeium), Theia (Eclipse Foundation), Code Server (for remote development). Microsoft introduced GitHub Copilot Workspace through VSCode extensions.