用于 (yòng yú) is a formal, written verb meaning 'to be used for/in' — it directly links a tool, method, or data to its purpose. Unlike 用来 (yòng lái), which is more colloquial and often introduces a verb phrase, 用于 is concise and common in official, technical, or academic contexts. It is not a synonym of 做 (zuò 'to do') or 使用 (shǐ yòng 'to use'); it focuses on the function or application, not the action of using.