They are very small text files that are stored on your computer when you visit our site.
Also the Cookie Notification plugin demo page will also generate a cookie for the purpose of the demo only.
Further our site uses Google Analytics and StatCounter which generate cookies on your computer.
Here is a more general way of explaining how cookies work by Google - read here.
This is how Google Analytics protects your data - Data privacy and security.
This is how to Opt-Out from Google Analytics.
StatCounter cookie usage - http://statcounter.com/about/cookies/
In the section "Third Party Advertiser Cookies" you can learn how to Opt-Out.