Czech is the Czech Republic's official language. Some of its more than 10 million native speakers are citizens of Serbia, Ukraine, Austria, Poland, and Bulgaria. Although Czech cannot be described as an overly complicated language, it can be challenging for beginners. This is because some of its words lack vowels, not to mention that its capitalization rules can be confusing. Factually, only about 59% of Czech speakers understand how to capitalize words correctly.
Slovak and Czech are mutually intelligible. Some linguists have even tried to argue that these two languages were dialects of one. Still, no substantial evidence has actually been found to support the same.