公共汽车是一种以中型或大型汽车（大客车/巴士）作为运送手段，以运输大量乘客的的大众运输服务。

公共汽车在中文地区中的名称不尽相同。

A bus (archaically also omnibus, multibus, motorbus) is a road vehicle designed to carry many passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker rigid bus, with larger loads carried by double-decker and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are used for longer-distance services. Many types of buses, such as city transit buses and inter-city coaches, charge a fare. Other types, such as elementary or secondary school buses or shuttle buses within a post-secondary education campus do not charge a fare. In many jurisdictions, bus drivers require a special licence above and beyond a regular driver's licence.