Copyright
Copyright is international through the Berne Union for the Protection of Literary and Artistic Property (or Berne Convention for short) which does not refer to the laws of any country in particular.
This means that individual copyright laws of different countries might be different to the main rules listed in the Convention but as a rule do not contravene or provide less copyright protection than the Berne Convention, provided the country in question is a member. Basically, according to the Convention, copyright provides international legal protection to makers of original artistic and literary works, making it illegal to reproduce or profit from the creative work of others.
There is no such thing as an international copyright that protects your work throughout the world, but countries that are members the Berne Convention and the Universal Copyright Convention (UCC) will provide protection of your wrk in those countries even if you are not a citizen or national. The requirement for protection is the same as for UK copyright protection: having the author / artists name on the work (or ascribed to it), preferably with the © symbol and the year of creation.
An excellent resource on copyright, including a discussion on international protection, can be found at www.whatiscopyright.org.