The term “tenement” simply refers to a building which is divided into apartments for the use of multiple residents, but it has come to have a pejorative meaning, thanks to the history of tenements around the world. Therefore, it is unusual to hear an ordinary apartment building referred to as a tenement, except in some isolated regions of the world where the term's negative meaning has not penetrated.

The defining characteristic of a tenement is that it is a building divided into three or more apartments, and these apartments are leased from a landlord who owns the entire building. Many buildings have vast numbers of apartments and multiple stories to accommodate them all.

In the United States, tenements housed the majority of new immigrants to the country in the 19th and early 20th century. These tenements were cramped, crowded, and poorly constructed. Often, multiple families lived in the same apartment together, to save rent, leaving minimal space, and the buildings were poorly ventilated. Many tenements also lacked water and basic sanitation, and they were probably extremely unpleasant to live in.

Tenements may have been unpleasant, but their landlords were often worse. Landlords would take advantage of new immigrants with price gouging tactics, intimidation, and other techniques designed to keep the tenants from complaining or reporting hazardous conditions. Tenement fires were rife, along with the spread of infectious disease. As a result of these conditions, the thought of a tenement conjures up cheaply made working class housing for many Americans, and this sense of the word has spread to many other regions of the world.

Tenements in New York City were particularly infamous, and numerous organizations crusaded to create protections for tenement residents and legislate at least basic measures for human decency, like minimum space requirements, mandatory air shafts for ventilation, and basic plumbing for the purpose of sanitation. Today, all construction in the United States is closely regulated, and people would be hard pressed to find tenement conditions as extreme as those which prevailed in the late 1800s, although housing of very poor quality still exists.

Many people associate tenements with slums, again thanks to the early tenements of the United States. In some regions of the word, high-quality apartment housing has devolved into tenements, creating slums where pleasant neighborhoods once existed. The rise of slums is caused by a number of factors, including changing fortunes, shifting property values, and increasing migration into cities from rural areas.