Setting email alerts in SharePoint is a great way to receive notification when something changes. This video will show you how to configure and use such alerts for a Document Library on both the complete Library as well as an individual item.
Email notifications need to used in moderation as it is very easy to become quickly swamped but the frequency of alerts SharePoint send by default. This video will also show you how to customise this frequency to ensure you only get the information you need, when you need it.
Although the video only show the alert configuration process on a Document Library it is possible to configure most elements in SharePoint for email alerts in the same manner.
Used appropriately, email alerts in SharePoint provide an important way to be kept up to date about information you are collaborating on within a team.