Technical Note: What are Delta Badges

Delta Badges show you the number of events, network events or alerts which have fired since you last visited a page.

On the left hand menu, small blue badges show you the number of events (on the Threat Hunting tab) or alerts (on the Policies tab) which have streamed in since you last visited these pages; giving you a quick overview of what's going on across your network.  Once you visit a particular page, the badge disappears, and will start counting afresh.