This feature was introduced in CRM Online 2016 Update 1 and CRM 2016 Service Pack 1 (on-premises).

you can Improve your products and services by enabling users to provide feedback and ratings for entity records in Microsoft Dynamics 365. For example, you can enable feedbacks and ratings for the Product entity to know user’s feedback on the products you sell, or on the Incident (case) entity to understand and improve the quality of your customer support team.

You can enable feedback and rating for both system and custom entities in Dynamics 365.

The Feedback entity stores the following information :

• Feedback title
• Feedback comments
• Feedback rating. You can also define a range for ratings by specifying a minimum and maximum (numerical) value for ratings. For example, a rating of 4 on the scale of 1-5.
• Normalized rating for feedback that is automatically calculated to show the specified user rating scaled to a value between 0 and 1 based on the minimum and maximum rating values.

please refer to the below post on how to enabled it for your OOB and Custom entities:

https://technet.microsoft.com/library/mt826657.aspx

i hope this helps!

cheers!