Automatic Data Processing — the ~$120B payroll, HR, and benefits giant founded in 1949, processing paychecks for roughly one in six American workers. ADP is often cited as the prototypical "deeply embedded infrastructure" SaaS: unsexy, sticky, high switching cost, and quietly compounding for decades. A useful counter-narrative when tech Twitter fetishizes growth-at-all-costs startups — ADP's moat is boredom and reliability.