The SharePoint Online platform is generally comprised of site collections, sites, web parts, and pages. A site is a website that contains various SharePoint objects such as pages, document libraries, or calendars. A site collection is a group of sites, normally organized by department, project, cross-functional group, or other business units. A page is an HTML web page. Pages can be basic with just displayed text or built from templates (such as Wiki or Publishing Portal) that may have different web parts preloaded.
Web parts are codeless widgets or apps that can be used to display or interact with information on a page:
In the preceding diagram, the Managers (Site) contains three web parts: a calendar, ...
