Are cookies kept private or are they publicly accessible?

Answer 1

Cookies are small text files stored locally (on your computer). They are meant to be harmless and only store data intended for use by the website that "gave them to you". For instance if you visited a website and were filling in a form, the "cookie" would hold that data incase you clicked away and then came back. That way you wouldn't have to re-fill in all that you had done previously. Cookies are supposed to expire after a time and should not be accessible to any other website or someone over the net. In theory cookies are viewable to you and the originating web site only. In practice however, depending on the web browser you use, there are exploits that can be used by various sites to get cookies from other sites as well. Also, some sites share such cookies between themselves.

Essentially and in practice, you have little control on who views your cookies, and that's why they are considered a security and privacy risk. Browsing with cookies disabled can be hard or impossible however, so it's a good policy to set up your browser to accept them but delete them when you close it.