An email alert (notification) can be set for certain lists within the site. Examples of such lists are News, Events Calendar, Discussions.
1. Go to the Master list, for example Discussions>All Discussions
2. Click on the "Actions" menu, and choose Alert Me.
3. Next, you can set the frequency of alerts. e.g. If you want to be alerted immediately something changes, or just once a day. You can change the alert settings at any time.