1. Public Suffix List

http://publicsuffix.org/ http/cookieの適用範囲

A "public suffix" is one under which Internet users can directly register names. 

It allows browsers to, for example:

• Avoid privacy-damaging "supercookies" being set for high-level domain name suffixes
• Highlight the most important part of a domain name in the user interface
• Accurately sort history entries by site

2011年9月29日現在のリストからjp関連を抜き出したものは添付ファイルにある。 -- ToshinoriMaeno 2011-09-29 05:06:09

http://publicsuffix.org/list/ /LIST FORMAT

/Formal Algorithm /Example

2. 目的

上位ドメインのクッキー（supercookies)を設定させないように使う。

• リストにないからと言って、安心するのはどうか。

ブラウザのcookieというものが欠陥だという考えもある。

• なぜ上位ドメインに対するcookieを保持させる必要があるのか。

そういうもので、DNSが制約されては、ドメイン売買の商売に差し支えるというのが、ICANNやJPレジストリの考えらしい。 -- ToshinoriMaeno 2011-09-29 07:29:47

The usefulness of this can be seen if we take the example of cookies.
In the past, browsers used an algorithm which only denied setting wide-ranging cookies
for top-level domains with no dots (e.g. com or org).
However, this did not work for top-level domains where only third-level registrations are allowed (e.g. co.uk).
In these cases, websites could set a cookie for .co.uk which would be passed onto every website registered under co.uk. 

Since there was and remains no algorithmic method of finding the highest level
at which a domain may be registered for a particular top-level domain
(the policies differ with each registry),
the only method is to create a list.
This is the aim of the Public Suffix List.