Word frequency refers to how often a specific word appears in a given text or set of texts. It is a useful measure in fields like linguistics, data analysis, and information retrieval, helping researchers understand language patterns, trends, and the importance of certain terms within a context. By analyzing word frequency, one can identify key themes and topics in a document. For example, in a news article, frequently used words may indicate the main subjects being discussed, while less common words might highlight unique or specialized information relevant to the story.