Why is there a red dot on my Apple Watch?

A red dot at the top of your Apple Watch screen indicates that you have an unread Notification.

Other status icons include:

• A lightning bolt means your Watch is charging.
• The lock icon means your device is locked with a passcode.
• A crescent moon icon means your Apple Watch is in Do Not Disturb Mode.
• An airplane shows that your Watch is in Airplane mode.
• The crossed out iPhone means your Apple Watch is no longer paired with your iPhone.
• This icon means there’s wireless activity or an active process happening.