Puzzled Signing-in in Mozilla!

I was signing in a website: I clicked on the Sign in button; but I could not enter the web page. The home page of the website kept on returning back as I repeated on and on this signing in business! I was shocked and wondered whether someone has hacked. I went on to check and confirm it in an another website; but that too returned the signing-in page - but with a note to check the browser's settings in the computer:

Your browser's cookie functionality is turned off. Please turn it on.

Yes, it is the Gmail that helped me to solve this perplexing problem: I had disabled by mistake the Accept cookies from sites check box instead of the Accept third-party cookies in Privacy tab of Option (Tools menu of Mozilla Firefox)! I felt greatly relieved then. You can go through this as a mock exercise and find out how Google helps you in it with its Account Help page.