Diacritical marks are symbols added to letters to alter their pronunciation or to distinguish between similar words. Common examples include the acute accent (´) in é and the umlaut (¨) in ö. These marks are essential in many languages, such as Spanish and German, where they can change the meaning of words. In addition to pronunciation, diacritical marks can indicate stress or tone in languages like Mandarin Chinese. They help clarify meaning and ensure accurate communication. Without these marks, written language could become ambiguous, leading to misunderstandings in both spoken and written forms.