A "public suffix" is a domain name under which Internet users can directly
register own names.

Browsers and other web clients can use it to
- avoid privacy-leaking "supercookies"
- avoid privacy-leaking "super domain" certificates [1]
- domain highlighting parts of the domain in a user interface
- sorting domain lists by site

Libpsl...
- has built-in PSL data for fast access
- allows to load PSL data from files
- checks if a given domain is a "public suffix"
- provides immediate cookie domain verification
- finds the longest public part of a given domain
- finds the shortest private part of a given domain
- works with international domains (UTF-8 and IDNA2008 Punycode)
- is thread-safe
- handles IDNA2008 UTS#46 (libicu is used by psl2c if installed)

[1] http://lists.gnu.org/archive/html/bug-wget/2014-03/msg00093.html

WWW: https://github.com/rockdaboot/libpsl