Users can subscribe to tags to receive notifications for the following activities:
1) New ideas
2) New comments
Steps to follow/unfollow tags:
1) Click on the desired tag to open the idea list that has that tag. For example: 'water' tag on this idea.
2) At the top right of the idea list, you will see Follow tag button. Click on this button to follow it.
3) To unfollow the tag, simply follow the first step and then click on the 'Following Tag' button which appears on the top right end of the list.