用来 (yòng lái) means 'to be used for (doing something)' and always introduces a purpose or function, followed by a verb phrase. Unlike 使用 (shǐ yòng), which means 'to use' an object directly, 用来 focuses on the object's intended function. It is similar to 用于 (yòng yú), but 用来 is more common in everyday speech, while 用于 is more formal and written.