If you click on "My groups", you will see a list of every group to which you belong. Every registered user is automatically a member of the 'New Tactics Community Members' group, but you may create or join as many other smaller groups as you like.

To join another group from the Groups directory, you "subscribe" to it. In some cases, the subscription is by invitation only, meaning that a group "administrator" or "manager" must invite you to subscribe. If the subscription is "closed", then the group administrator is the only one who can subscribe you or unsubscribe you.

"Email notification" is the service available only to members of a group (those who have a subscription to that group). You may choose to receive messages by email when new content is posted in any of your groups. This is useful if your internet connection allows you to check email more reliably that browsing the web. This setting is something you can control for all of your groups together, or selectively for each one (see How do I stop or start receiving email messages when something new is posted to the website?)