Feedback is help for a website owner.

This may consist of compliments or criticism on the website, its layout, content, structure or other things they as an administrator are working on....

This is private information between a reader and the website owner, and is limited to it's purpose of providing help and suggestions from one party to another.

The website owner may ask readers for feedback, but in his/her own interest of public presentation, they should suggest a platform (like the one WA provides through the siterubix (lightblue-colored) portal), which is designated for such interchange, or it can be done through private messages or mails.

Occasionally, someone will specifically ask for it in a blog at WA, in which case it's an invitation, and acceptable.