Tabs are useful for grouping Streams. You can have one or multiple Streams inside of one Tab.
To create a new tab: Click on the "+" button on the tab bar located at the top of the Streams page, then name it and hit "Enter".
To rename a Tab: Double click on the Tab's name and edit it, then hit "Enter".
To delete a Tab: Click on the "X" button next to the Tab you want to be removed. Note that all the Streams in this Tab will be removed as well. Confirm your action by clicking the "Remove" button on the pop-up window below.