Cookies Useful or Inappropriate:
Cookies are useful when Period cleaning is require regularly.
Some place cookies are useful at same time hackers can uses these cookies and it became an inappropriate usages which leads to hack your system.
Some web site prompt saying this website are enable for cookies. Purpose cookies to end user to keep user login pages and immediately load the user customized web pages.
As good practice cookies tracking has to be cleaned in schedule methods.
Every Browser keeps cookies records if we enabled to particular web site. Sometime cookies are shared across the browser in same laptop or desktop.