As your mailbox grows in size, you may want to flag specific messages so that you can spot them more easily in the Inbox. Gmail allows you to star important messages, making them stand out in the Inbox, and also making it possible to show starred messages only, hiding all other messages from view.
To choose which stars can be used on your messages:
Click on the Settings cog in the right-hand corner of the screen
Choose See all settings
Next to Stars, choose to use 1 star, 4 stars or all stars
Drag the stars you wish to use into the In Use list
Click on Save Changes when complete
You can now star messages as required:
To star a single message, click on the star icon next to the message’s check box. The default yellow star will be applied. Click on the star again to change the to a blue star, then a green circle (with a tick), then a red circle (with an exclamation mark)
To star multiple messages, select the messages, then click on the More button and choose Add Star - you can only apply the default yellow star using this method
To remove stars from selected messages, click on More button, then on Remove Star
To view all starred messages, click on the Starred link on the left-hand side of the screen. All messages without a star will be hidden until you click back on the Inbox link again.