Hutong are a type of narrow street or alley commonly associated with northern Chinese cities, especially Beijing. 

In Beijing, hutongs are alleys formed by lines of siheyuan, traditional courtyard residences. Many neighbourhoods were formed by joining one siheyuan to another to form a hutong, and then joining one hutong to another. The word hutong is also used to refer to such neighbourhoods.

Hutongs represent an important cultural element of the city of Beijing. Thanks to Beijing's long history and status as capital for six dynasties, almost every hutong has its anecdotes, and some are even associated with historic events. In contrast to the court life and elite culture represented by the Forbidden City, Summer Palace, and the Temple of Heaven, the hutongs reflect the culture of grassroots Beijingers. The hutongs are residential neighborhoods which still form the heart of Old Beijing. 

- Wikipedia