Croatian is Croatia's official language. The European Union, Austria, Bosnia and Herzegovina, and Serbia also recognize it as one of their official languages. The Czech Republic, Italy, and Hungary are some countries that identify it as a minority language, too. It's the standardized version of Serbo-Croatian, and it belongs to the Indo-European language family. It has over five million native speakers, mainly the Croats in Bosnia and Herzegovina, Croatia, Romania, Montenegro, and Serbia.
It's officially taught at every university in Croatia. An excellent grasp of it provides a gateway to other major languages. After knowing basic Croatian, it's easy to learn Bosnian, Bulgarian, and Serbian.