Fake news, challenges to freedom of opinion and freedom of the press—these problems are rampant today and increasingly a threat in Europe too. In such times, we need to reflect on one of the most important assets of our democracy: the right to form one's own opinion, enshrined in Article 5 of Germany's Constitution, and the subject of this report. But what are the limits on freedom of opinion? Who shapes the public debate? Is the one who screams the loudest always right? The ABCs of freedom of opinion playfully guides readers through the most important buzz words on the subject—from A for alternative facts to C for censorship. Each letter poses a question, giving readers the opportunity to form their own opinion.