Ablaut is a linguistic phenomenon that involves the systematic variation of vowel sounds within related words. It is often found in the inflection of verbs, particularly in languages like German and English. For example, the verb "sing" has different forms: "sang" (past tense) and "sung" (past participle), showcasing how vowel changes can indicate grammatical differences. This vowel alteration is a key feature in the study of historical linguistics and helps linguists understand the evolution of languages. Ablaut patterns can reveal connections between words and their meanings, contributing to the broader understanding of language development and structure.