Green shows the countries you want to live in, because they have little to no internet censorship. Yellow reveals countries that you might not want to stay in too long, because they might increase censorship in the future. If you love the internet, you should probably avoid every other colour because they all have different degrees of censorship, with pink being the most pervasive (grey is not classified).
The OpenNet Initiative pegs the colours as such:
- Pervasive - A large portion of content in several categories is blocked. (Pink)
- Substantial - A number of categories are subject to a medium level of filtering or many categories are subject to a low level of filtering. (Light Pink)
- Selective - A small number of specific sites are blocked or filtering targets a small number of categories or issues. (Light Yellow)
- Changing Situation - It is suspected, but not confirmed, that Web sites are being blocked. (Yellow)
- Little or No Censorship - No evidence of blocked Web sites, although other forms of controls may exist. (Green)
The classification of censorship depends on political censorship like human rights and government opposition, social censorship (which is basically like porn), conflict/security censorship which deals with militant groups and various internet tool censorship like e-mail and search. To no one's surprise, countries like China and Iran are the worst offenders of internet censorship. [Wikipedia, Maps on the Web]