A gap year, also known as a sabbatical year, is a year's break between high school and college/university, aimed at promoting a mature outlook with which to absorb the benefits of higher education. It also indicates a break before entry into graduate school. Activities range across advanced academic courses, extra-academic courses and non-academic courses, such as pre-college math courses, language studies, learning a trade, art studies, volunteer work, travel, internships, sports, cultural exchanges and more.
In 1967 Project Trust sent its first three volunteers to Ethiopia from the UK.
In 1972, Gap Activity Projects was founded in the UK and later renamed Lattitude Global Volunteering in 2008.
In 1973, Graham "Skroo" Turner set up the company Topdeck, one of the first tour operators.
In 1978, the Prince of Wales and Colonel John Blashford-Snell began what is now known as Raleigh International by launching Operation Drake, an expedition voyage around the world following Sir Francis Drake's route.
In the United States, the gap year idea was promoted by Cornelius H. Bull to allow students more time to grow as a person, in 1980.
In 2016 the Gap Year idea reached new levels of popularity as then US President Obama's daughter, Malia, announced her Gap Year plans. 
Australians and New Zealanders have a tradition of travelling overseas independently at a young age. In New Zealand this is known as "doing an OE" (Overseas experience). Sometimes this is limited to one year, but often Australians and New Zealanders will remain overseas for longer, with many working short-term in service industry jobs to fund their continuing travels. Europe and Asia are popular destinations for Gap Year travels. In Australia, exchange programs and youth benefits provide many opportunities for young people to broaden their minds through travel in a gap year. The concept of the OE is so ingrained in the New Zealand psyche that the national tax department devotes a section of its website telling people how doing their OEs will contribute to the country.
The Time Credit system in Belgium entitles employees of one year per lifetime of absence from their job, in order to prevent burn-out and to provide an opportunity to pursue other important things in life.
Denmark has sought to limit the number of students who take a year out, penalising students who delay their education to travel abroad or work full-time. In 2006, it was announced that fewer students than before had taken a year out. In April 2009, the Danish government proposed a new law which gives a bonus to students who refrain from a year out.
In Ghana, most senior high school leavers have a year out from August to the August of the following year although this is not mandatory.
Israel has also become a popular gap year travel destination for thousands of young Jewish adults from abroad each year. There are over 10,000 participants annually who take a Masa Israel Journey gap year.
Nigerians typically enroll for a year long National service after college. It starts with a 3-week paramilitary boot-camp, from there, they are posted to a Government institution for the rest of the year.
There is no idea of gap years in Russia and other post-Soviet countries at all. Men who weren't accepted to university are drafted into the army for a year.
In the Republic of South Africa a year off is common. This is specifically for more affluent classes. School leavers often travel abroad for getting further life experience. It is not uncommon for gap year students in South Africa to go to Cape Town to get life experience. It is not mandatory but fairly common for individuals to volunteer during this time doing animal welfare or tree planting.
In the United Kingdom, the practice of taking a gap year - seen as an interim period of 7 or 8 months between completing secondary education and starting university - began to develop in the 1970s ("Martin, 2010). The period was seen as a time for gaining life experience through travel or volunteering. Universities appear to welcome post-gap-year applicants on the same basis as those going straight to university from previous education.
The number of students aged 18 opting to defer their university place in order to take a gap year reached a peak of 21,020 in 2008. This figure crashed to 7,320 in 2011 - a year before the introduction of greatly increased tuition fees by the Conservative/Lib Dem (Cameron/Clegg) coalition government. Deferrals in 2016 were near their peak again although Year Out Group states its members now take more bookings from students outside the UK. Shorter gap style experiences (volunteering, expeditions, courses and work placements) are gaining in popularity, as they can be taken without the need to take a full year out of study or work.
In the United States, the practice of taking a "year off" remains the exception, but is gaining in popularity. Many colleges, most notably Harvard University and Princeton University, are now encouraging students to take time off, and some have even built gap year-like programs into the curriculum. Several high schools now have counselors specifically for students interested in taking a gap year. Taking a year off has recently become slightly more common for Americans, with prevailing reasons as a feeling of being burned out of classroom education and a desire to understand oneself better. Some 40,000 Americans participated in 2013 in sabbatical programs, an increase of almost 20% since 2006, according to statistics compiled by the American Gap Association. Universities such as Georgetown University, New York University,Amherst College, Princeton University, Harvard University, Massachusetts Institute of Technology, Middlebury College,Yeshiva University, and Reed College have formal policies allowing students to defer admission. The Tufts University has a new program that seeks to remove financial barriers that prevent students with no money from taking a gap year after completing secondary to travel or do volunteer work in other countries.
Some formal gap year programs can cost as much as $30,000, but there are also cheaper alternatives becoming more widely available; some do this by offering room and board. For example, the National Civilian Community Corps, an AmeriCorps program, offers 18-24 year olds (no age limit for Team Leaders) an all expense paid gap year (room & board, meals, transportation, etc.) in exchange for a 10-month commitment to National and Community service. AmeriCorps NCCC members travel the country in diverse teams and perform a variety of tasks such as rebuilding trails in national parks, responding to natural disasters or working as mentors for disadvantaged youth. As with most AmeriCorps programs, service members receive an education award of approximately $6,000 upon completion of their service that can be used toward qualified educational expenses or student loans. The zero cost to the member model AmeriCorps offers makes it an attractive alternative to costly gap year programs while leveraging taxpayer dollars to strengthen American communities. Additionally, new federal partnerships such as FEMA Corps offer traditional gap year seekers an immersive professional and team building experience that can serve as a launch pad for their careers.
Some government programs designed to help students afford college prohibit students from taking a gap year. For example, the Tennessee Promise program requires that students must "Attend full-time and continuously at an eligible postsecondary institution as defined in T.C.A. § 49-4-708 in the fall term immediately following graduation or attainment of a GED or HiSET diploma; except that a student enrolling in a Tennessee College of Applied Technology (TCAT) may enroll in the summer prior to the fall term." 
In Venezuela, students from elite schools generally do their undergraduate studies outside of Venezuela. Gap years were unknown in Venezuela until educational consultant Nelson Agelvis, then counselor of the Moral y Luces Herzl-Bialik Jewish school in Caracas, insisted on having applicants to US colleges do them. The students went to leadership courses in Israel, PG years at elite US schools, tutorial colleges in the UK, work internships, language centers across the globe, and exploration gap years in remote countries. Today, the practice is widespread and Venezuela is a big economic contributor to the gap year, college studies and English studies industries, especially in countries such as Ireland.
In Yemen, a defer year is mandatory between secondary school (High-School) and University. Unless one attends a private university, they must wait one year after secondary school before applying to University. Until the nineties it was mandatory for male graduates to go to the army for one year, and to teach in a school or work in a hospital for female graduates (and for men who cannot attend the army for health reasons).
In Romania, after finishing high school, for some universities you have to take an admission exam. People who don't pass it sometimes take a gap year to study for that exam and usually they pass it the second time. For example, doing this if you did not get into a medical or engineering school is pretty common.