High-Level Architecture

At a high level, Moodle usually includes the following components:

Component	Simple Explanation
Web browser	The interface used by students, teachers, and administrators
Web server	Runs Moodle and responds to web requests
Moodle application code	PHP application files that provide Moodle functionality
Database	Stores users, courses, grades, settings, activity data, and many records
moodledata	Stores uploaded files, cache data, sessions, temporary files, and generated content
Cron	Runs background tasks such as sending emails, processing completion, and cleanup
Authentication services	Optional systems used for login, such as LDAP, SSO, or OAuth2
Email service	Sends notifications and password reset messages

A simplified request flow:

User Browser → Web Server → Moodle Application → Database / moodledata → Response to Browser

Some tasks happen in the background:

Cron Scheduler → Moodle Scheduled Tasks → Email, cleanup, reports, completion, notifications