A boarding school is a school where some or all pupils not only study, but also live during term time, with their fellow students and possibly teachers. The word 'boarding' is used in the sense of "bed and board", that is, food and lodging. Most boarding schools also have day students who are local residents or children of faculty.
Many independent schools in the Commonwealth of Nations are boarding schools. Boarding school pupils (a.k.a. "boarders") normally return home during the school holidays and, often, weekends, but in some cultures may spend the majority of their childhood and adolescent life away from their families. In the United States, boarding schools sometimes comprise grades 7 through 12, but the most reputable cover only the high school years, from the 9th through the 12th grades. Some also feature military training, though this is generally offered only at specialized schools. Many New England boarding schools traditionally offer a post-graduate year of study, unknown in many parts of the U.S., in order to help students prepare for college entrance.
A boarding school is when the pupils sleep, eat and work in or near the school grounds. The term boarding school often refers to classic British boarding schools and many boarding schools are modeled on these. 
A typical modern fee-charging boarding school has several separate residential houses, either within the school grounds or in the neighborhood of the school. Pupils generally need permission to go outside defined school bounds; they may be allowed to venture further at certain times.
A number of senior teaching staff are appointed as housemasters, housemistresses or residential advisors, each of whom takes quasi-parental responsibility for perhaps 50 pupils resident in their house, at all times but particularly outside school hours. Each may be assisted in the domestic management of the house by a housekeeper often known as matron, and by a house tutor for academic matters, often providing staff of each sex. Nevertheless, older pupils are often unsupervised by staff, and a system of monitors or prefects gives limited authority to senior pupils. Houses readily develop distinctive characters, and a healthy rivalry between houses is often encouraged in sport. See also House system.
Annexed to the house staff accommodation, houses usually include study-bedrooms or dormitories, a dining room or refectory where pupils take meals at fixed times, and a library, hall or cubicles where pupils can do their homework. Houses may also have common rooms for television and relaxation, kitchens for snacks, and perhaps computer, ping-pong or billiards rooms, together with facilities such as cloakrooms and cycle sheds. Some facilities may be shared between several houses.
In some schools each house has pupils of all ages, in which case there is usually a prefect system, which gives older pupils some privileges and some responsibility for the welfare of the younger ones. In others, separate houses accommodate needs of different years or classes.
Each pupil has an individual timetable, which in the early years allows little discretion. Pupils of all houses and day pupils are taught together in school hours, but boarding pupils' activities extend well outside school hours and a period for homework. Sports, clubs and societies (e.g. amateur dramatics, or political and literary speakers, or hobby clubs), or excursions (to performances, shopping or perhaps a school dance) may run until lights out. As well as the usual academic facilities such as classrooms, halls, libraries and laboratories, boarding schools often provide a wide variety of facilities for extracurricular activities such as music rooms, gymnasia, sports fields and school grounds, boats, squash courts, swimming pools, cinemas and theatres. A school chapel is often found on site. Day pupils often stay on after school to use these facilities.
British boarding schools have three terms a year, approximately twelve weeks each, with a few days' half-term holiday during which pupils are expected to go home or at least away from school. There may be several exeats or weekends in each half of the term when pupils may go home or away. Boarding pupils nowadays often go to school within easy traveling distance of their homes, and so may see their families frequently; families are encouraged to come and support school sports teams playing at home against other schools.
Most school dormitories have a "lights out" time when the pupils are required to be in bed, depending on their age, and perhaps a later time after which no talking is permitted; such rules may be difficult to enforce, and pupils may often try to break them, for example by reading surreptitiously by torchlight or escaping on nocturnal excursions. Pupils sharing studies are less likely to disturb others and may be given more latitude.
Some boarding schools have only boarding students, while others have both boarding students and day students who go home at the end of the school day. Day students are often known as day boys or day girls. Some schools also have a class of day students who stay throughout the day including breakfast and dinner, which they call semi-boarders. Schools that have both boarding and day students sometimes describe themselves as semi boarding schools or day boarding schools. Many schools also have students who board during the week but go home on weekends: these are known as weekly boarders, quasi-boarders, or five-day boarders.
Day students and weekly boarders may have a different and perhaps unfavourable view of the day school system, as compared to children who attend day schools without any boarding facilities. These students relate to a boarding school life, even though they do not totally reside in school; however, they may not completely become part of the boarding school experience. On the other hand, these students have a different view of boarding schools as compared to full-term boarders who go home less frequently, perhaps only at the end of a term or even the end of an academic year.
Boarding schools are a form of residential school; however, not all residential schools are "classic" boarding schools. Other forms of residential schools include:
In the UK, almost all boarding schools are independent schools, which are not subject to the national curriculum or other educational regulations applicable to state schools. Nevertheless there are some regulations, primarily for health and safety purposes, as well as the general law. The Department for Children, Schools and Families, in conjunction with the Department of Health of the United Kingdom, has prescribed guidelines for boarding schools, called the National Boarding Standards.
One example of regulations covered within the National Boarding Standards are those for the minimum floor area or living space required for each student and other aspects of basic facilities. The minimum floor area of a dormitory accommodating two or more students is defined as the number of students sleeping in the dormitory multiplied by 4.2 m², plus 1.2 m². A minimum distance of 0.9 m should also be maintained between any two beds in a dormitory, bedroom or cubicle. In case students are provided with a cubicle, then each student must be provided with a window and a floor area of 5.0 m² at the least. A bedroom for a single student should be at least of floor area of 6.0 m². Boarding schools must provide a total floor area of at least 2.3 m² living accommodation for every boarder. This should also be incorporated with at least one bathtub or shower for every ten students.
These are some of the few guidelines set by the department amongst many others. It could probably be observed that not all boarding schools around the world meet these minimum basic standards, despite their apparent appeal.
The practice of sending children to other families or to schools so that they could learn together is of very long standing, recorded in classical literature and in UK records going back over a thousand years. In Europe a practice developed by early mediaeval times of sending boys to be taught by literate clergymen, either in monasteries or as pages in great households. The school often considered the world's oldest boarding school, The King’s School, Canterbury, counts the development of the monastery school in around 597 AD to be the date of the school's founding. The author of the Chronicle of Ingulph recalls being tested on his grammar by Edward the Confessor's Queen Editha in the abbey cloisters as a Westminster schoolboy, in around the 1050s. Monastic schools as such were generally dissolved with the monasteries themselves under Henry VIII, although for example Westminster School was specifically preserved by the King's letters patent and it seems likely that most schools were immediately replaced. Winchester College founded by Bishop William of Wykeham in 1382 claims to be the oldest boarding school in continual operation.
Boarding Schools manifest themselves in different ways in different societies. For example, in some societies children start boarding school at an earlier age than in others. In some societies, a tradition has developed in which families send their children to the same boarding school for generations.
One observation that appears to apply globally is that a significantly larger number of boys than girls attend boarding school and for a longer span of time.
Boarding schools in England started before medieval times, when boys were sent to be educated at a monastery or noble household, where a lone literate cleric could be found. In the 12th century, the Pope ordered all Benedictine monasteries such as Westminster to provide charity schools, and many public schools started when such schools attracted paying pupils. These public schools reflected the collegiate universities of Oxford and Cambridge, as in many ways they still do, and were accordingly staffed almost entirely by clergymen until the 19th century. Private tuition at home remained the norm for aristocratic families, and for girls in particular, but after the 16th century it was increasingly accepted that adolescents of any rank might best be educated collectively. The institution has thus adapted itself to changing social circumstances over 1000 years.
Boarding preparatory schools tend to reflect the public schools they feed. They often have a more or less official tie to particular schools.
The classic British boarding school became highly popular during the colonial expansion of the British Empire. British colonial administrators abroad could ensure that their children were brought up in British culture at public schools at home in the UK, and local rulers were offered the same education for their sons. More junior expatriates would send their children to local British-run schools, which would also admit selected local children who might travel from considerable distances. The boarding schools, which inculcated their own values, became an effective way to encourage local people to share British ideals, and so help the British achieve their imperial goals.
One of the reasons sometimes stated for sending children to boarding schools is to develop wider horizons than their family can provide. A boarding school a family has attended for generations may define the culture parents aspire to for their children. Equally, by choosing a fashionable boarding school, parents may aspire to better their children by enabling them to mix on equal terms with children of the upper classes. However, such stated reasons may conceal other reasons for sending a child away from home.    These might apply to children who are considered too disobedient or underachieving, children from families with divorced spouses, and children to whom the mother or parents do not relate much.   These reasons are rarely explicitly stated, though the child might be aware of them.  .
In 1998 there were 772 private-sector boarding schools in England, and 100,000 children attending boarding schools all over the United Kingdom. In England they are an important factor in the class system. Most other societies decline to make boarding schools the preferred option for the upbringing of their children, except in former British colonies; in India, Nigeria, and other former African colonies of Great Britain, for example, boarding schools are one of the preferred modes of education; in Ghana the majority of the secondary schools are boarding. In some countries, such as New Zealand and Sri Lanka, a number of state schools have boarding facilities. However these state boarding schools are frequently the traditional single-sex state schools, whose ethos is much like that of their independent counterparts. Furthermore, the proportion of boarders at these schools is often much lower than at independent boarding schools, typically around 10%.
The Swiss government developed a strategy of fostering private boarding schools for foreign students as a business integral to the country's economy. Their boarding schools offer instruction in several major languages and have a large number of quality facilities organized through the Swiss Federation of Private Schools.
In the United States, boarding schools for students below the age of 13 are called junior boarding schools, and are not as common and not as encouraged as in the United Kingdom and India. The oldest junior boarding school in the United States is the Fay School in Southborough, Massachusetts. Boarding schools for this age group are often referred to as prep schools. Some notable examples are Choate Rosemary Hall, Woodberry Forest School, The Hotchkiss School, Kent School, The Hill School, Deerfield Academy, Northfield Mount Hermon School, Phillips Exeter Academy, Phillips Academy Andover, The Lawrenceville School, St. Paul's School, and Canterbury School (Connecticut), the state's first Catholic Boarding School.
In the late 1800s, the United States government undertook a policy of educating Native American youth in the ways of the dominant Western culture so that Native Americans might then be able to assimilate into Western society. At these boarding schools, managed and regulated by the government, Native American students were subjected to a number of tactics to prepare them for life outside their reservation homes. 
In accordance with the assimilation methods used at the boarding schools, the education that the Native American children received at these institutions centered on the dominant society’s construction of gender norms and ideals. Thus boys and girls were separated in almost every activity and their interactions were strictly regulated along the lines of Victorian ideals. In addition, the instruction that the children received reflected the roles and duties that they were to assume once outside the reservation. Thus girls were taught skills that could be used in the home, such as "sewing, cooking, canning, ironing, child care, and cleaning"  (Adams 150). Native American boys in the boarding schools were taught the importance of an agricultural lifestyle, with an emphasis on raising livestock and agricultural skills like "plowing and planting, field irrigation, the care of stock, and the maintenance of fruit orchards" (Adams 149). These ideas of domesticity were in stark contrast to those existing in native communities and on reservations: many indigenous societies were based on a matrilineal system where the women’s lineage was honored and the women’s place in society respected. For example women in indigenous communities held powerful roles in their own communities, undertaking tasks that Western society deemed only appropriate for men: indigenous women could be leaders, healers, and farmers.
While the Native American children were exposed to and were likely to adopt some of the ideals set out by the whites operating these boarding schools, many resisted and rejected the gender norms that were being imposed upon them. See also: Carlisle Indian Industrial School in Carlisle, Pennsylvania.
It is claimed that children may be sent to boarding schools to give more opportunities than their family can provide. However, that involves spending significant parts of one's early life in what may be seen as a total institution  and possibly experiencing social detachment, as suggested by social-psychologist Erving Goffman.  This may involve long-term separation from one's parents and culture, leading to the experience of homesickness    and may give rise to a phenomenon known as the 'TCK' or third culture kid 
Some modern philosophies of education, such as constructivism and new methods of music training for children including Orff Schulwerk and the Suzuki method, make the everyday interaction of the child and parent an integral part of training and education. The European Union-Canada project "Child Welfare Across Borders" (2003) , an important international venture on child development, considers boarding schools as one form of permanent displacement of the child. This view reflects a new outlook towards education and child growth in the wake of more scientific understanding of the human brain and cognitive development.
Concrete numbers have yet to be tabulated regarding the statistical data for the ratio of the boys that are sent to boarding schools, the total number of girls, the total number of children in a given population in boarding schools by country, the average age across populations when children are sent to boarding schools, and the average length of education (in years) for boarding school students.
Boarding schools and their surrounding settings and situations have become a genre in British literature with its own identifiable conventions. (Typically, protagonists find themselves occasionally having to break school rules for honourable reasons the reader can identify with, and might get severely punished when caught - but usually they do not embark on a total rebellion against the school as a system.)
Notable examples of the school story include:
The setting has also been featured in notable North American fiction:
There is also a huge boarding-school genre literature, mostly uncollected, in British comics and serials from the 1900s to the 1980s.
The sub-genre of books and films set in a military or naval academy has many similarities with the above.