You can categorize emails using generic and descriptive labels.

How to create a label:

1- Go your inbox from the right side bar

2- Click on the "Plus" icon on the right side on "Labels",

3- Enter "Label Title" and "Label Color",

4- And done.

How to edit a label:

1- Open up your Labels list from your inbox,

2- Select the label you'd like to change,

3- Edit title or color as you wish.

How to add a label to an email?

You can add labels in bulk and for each thread of emails.

How to remove a label?

1- Open the email you'd like to remove the label from.

2- Click on "cross" icon on the top to remove the label.