lua-psl is a set of lua bindings to libpsl, a C library that handles the
Public Suffix List (PSL).

The PSL is a list of domains where there may be sub-domains outside of the
administrator's control, e.g. the administrator of '.org' does not manage
'NetBSD.org'.

This list has found use in many internet technologies including:

  - preventing cross-domain cookie leakage
  - allowance of issuing wildcard TLS certificates

More information can be found at publicsuffix.org