By default Magento includes the option to allow customers to tag your products. When a customer tags a certain product, the tag appears as pending and must be approved before it can show up on the product page.
Let’s add a tag to our product, approve it and see how it then shows up on the product page. To add a tag to a product, simply write the tag word in the Add Your Tags: field available on the product page and click Add Tags. We’ll add “Great” as a tag. A confirmation message will show up saying that the tag has been accepted for moderation