An LMS (Learning Management System) is a software platform for delivering educational content, managing students, tracking progress, and issuing certificates. It includes course delivery (video, documents, quizzes), student dashboards (progress, grades, transcripts), instructor tools (grading, communication), and analytics (completion rates, performance). LMS platforms power online education (universities, corporate training, skill development). Scaling LMS to 1M+ students requires careful engineering: content delivery (fast loading), database optimization (millions of enrollment records), analytics (student performance insights).