If you breed two Pokemon from different countries, then the odds of hatching a shiny are changed from 1/8192 to 1/1365, so it multiplies the chance by 6. This is known as the Masuda Method.
The method is named after Game Freak director Junichi Masuda, who
programmed it into Pokémon Diamond and Pearl. He documented the method
in his blog, where he mentioned a way that "rare colored Pokémon's Egg
can be found little easier." The mechanics behind the method were
discovered by Smogon.