The Group tab gives a graphical representation of a company's parents a subsidiaries, allowing you to quickly and easily understand otherwise complex and indecipherable relationships.
The ultimate parent of the group of companies will always be in red, and each subsequent change in colour represents a different level in the corporate family tree.
Double clicking a company brings it to the centre of the page, and reveals any further subsidiaries it has.
Single clicking a company brings up a preview card with basic information on the company - you can click through to individual company pages from these cards to investigate further.
You can easily add all the companies in one group to a list using the button in the top left of the group graph.