The phrase common room is used especially in British and Canadian English to describe a type of shared lounge, most often found in dormitories

Dormitory

A dormitory, often shortened to dorm, in the United States is a residence hall consisting of sleeping quarters or entire buildings primarily providing sleeping and residential quarters for large numbers of people, often boarding school, college or university students...

, at (for example) universities

University

A university is an institution of higher education and research, which grants academic degrees in a variety of subjects. A university is an organisation that provides both undergraduate education and postgraduate education...

, college

College

A college is an educational institution or a constituent part of an educational institution. Usage varies in English-speaking nations...

s, military base

Military base

A military base is a facility directly owned and operated by or for the military or one of its branches that shelters military equipment and personnel, and facilitates training and operations. In general, a military base provides accommodations for one or more units, but it may also be used as a...

s, hospital

Hospital

A hospital is a health care institution providing patient treatment by specialized staff and equipment. Hospitals often, but not always, provide for inpatient care or longer-term patient stays....

s, rest homes, hostel

Hostel

Hostels provide budget oriented, sociable accommodation where guests can rent a bed, usually a bunk bed, in a dormitory and share a bathroom, lounge and sometimes a kitchen. Rooms can be mixed or single-sex, although private rooms may also be available...

s, and even minimum-security prison

Prison

A prison is a place in which people are physically confined and, usually, deprived of a range of personal freedoms. Imprisonment or incarceration is a legal penalty that may be imposed by the state for the commission of a crime...

s. It is generally connected to several private rooms, and may incorporate a bathroom

Bathroom

A bathroom is a room for bathing in containing a bathtub and/or a shower and optionally a toilet, a sink/hand basin/wash basin and possibly also a bidet....

. However, they may also be found in day school

Day school

A day school—as opposed to a boarding school—is an institution where children are given educational instruction during the day and after which children/teens return to their homes...

s and sixth form

Sixth form

In the education systems of England, Wales, and Northern Ireland, and of Commonwealth West Indian countries such as Barbados, Trinidad and Tobago, Belize, Jamaica and Malta, the sixth form is the final two years of secondary education, where students, usually sixteen to eighteen years of age,...

s.

Regular features include couch

Couch

A couch, also called a sofa, is an item of furniture designed to seat more than one person, and providing support for the back and arms. Typically, it will have an armrest on either side. In homes couches are normally found in the family room, living room, den or the lounge...

es, television

Television

Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...

s, coffee table

Coffee table

A coffee table, also called a cocktail table, is a style of long, low table which is designed to be placed in front of a sofa, to support beverages , magazines, books , and other small items to be used while sitting, such as beverage coasters. Coffee tables are usually found in the living room or...

s, and other generic lounge furniture

Furniture

Furniture is the mass noun for the movable objects intended to support various human activities such as seating and sleeping in beds, to hold objects at a convenient height for work using horizontal surfaces above the ground, or to store things...

 for socializing.

Depending on its location and purpose of use, a common room may be known by another name. For instance, in mental hospital

Mental Hospital

Mental hospital may refer to:*Psychiatric hospital*hospital in Nepal named Mental Hospital...

s, where access is usually restricted to the daytime hours, this type of room is often called a "day room".