GitHub
World's largest code hosting platform — 100M+ developers. Tom Preston-Werner, Chris Wanstrath, PJ Hyett, 2008. Microsoft acquired for $7.5B in 2018.
Pull requests + issues + social coding revolutionized open source. Major products: Actions (CI/CD), Codespaces (cloud dev environments), Copilot (AI pair programming, 2021), Packages (artifact registry), Pages (static hosting). Competitors: GitLab (full DevOps platform), Bitbucket (Atlassian), Codeberg (non-profit). Octocat is the mascot. Microsoft acquisition drove many to Codeberg/sourcehut at the time.