<answer>Czech</answer>, the official language of the <answer>Czech</answer> Republic (a member of the European Union since 2004), is one of the EU's official languages and the 2012 Eurobarometer survey found that <answer>Czech</answer> was the foreign language most often used in Slovakia. Economist Jonathan van Parys collected data on language knowledge in Europe for the 2012 European Day of Languages. The five countries with the greatest use of <answer>Czech</answer> were the <answer>Czech</answer> Republic (98.77 percent), Slovakia (24.86 percent), Portugal (1.93 percent), Poland (0.98 percent) and Germany (0.47 percent).
What is the official language of the Czech republic?
Czech