This section gives you a really nice overview of your domain's usage metrics. You can specify a time period in the top right.

In this section you can get more detailed reports for Google Apps, Devices or Users for your specified time period.

Admin

This is a really useful tool and logs every administrative change made from user creation to settings changes. We strongly recommend that you don't use generic admin@yourschool.com accounts, but instead grant individuals Admin privileges as this helps with auditing purposes.

Login

Use this audit to search for failed or suspicious login attempts. Note that the IP address is also logged. You can set alerts for any audit to automatically alert you (e.g. malicious login attempt).

Drive

This powerful audit tool gives you a complete overview of all Drive usage across your domain. It's really useful if you want to find out which user deleted a file or folder, or quickly find all files that are publicly shared.

Token

This logs every time a user grants access to an app or service with API access.