老师 (lǎo shī) means teacher and is both the occupational title and a common form of address. 老 is an honorific prefix (literally old, conveying respect) and 师 means master or teacher. In Chinese schools and universities 老师 is used as an address for any teacher, similar to how students say sir or miss in English. It can follow a surname: 王老师 (Teacher Wang). In broader culture, 老师 is used respectfully for any professional with expertise.