See: Pages Overview
There are five "System Pages" which are available at everywhere you go on your site: Home, Learn, Share, Discuss, & Connect. These can be customized to suit your needs via Widgets. The names & icons can also be customized.
Your default Page. Where you start when you log in or first enter the site. Generally contains announcements, general information, each user's required but incomplete training, etc.
The Learn Library is where the mass of your modules will be accessed.
Where admins and regular users alike upload media to share with other users.
Useful as areas for discussions or in-depth announcements. Often used as newsletters, FAQs, or similar functions.
Often used for a steam of Recognition Messages, birthday & anniversary announcements, etc.