The Himalayas are a range of mountains in Asia. The Himalaya proper stretches from the Indus river in Pakistan, through India, Nepal, and Bhutan, and ends at the Bramaputra River in eastern India. The Greater Himalaya complex of mountains includes the Himalayas and some related ranges. On the eastern end, the Hengduan Range — which includes the Three parallel rivers, a in China — forms a T shape with that end of the Himalayas.
On the west, the Himalayas connect to a large area of high ground called the Pamir Knot, also a . Several other ranges extend in various directions from the knot — the Karakoram, running east parallel to the Himalaya and north of it, the Hindu Kush running southwest into Afghanistan, the Tian Shan Range running north, and the Kunlun Range northeast. All those ranges, and the Pamir Knot, include peaks over 7000 m.
The Himalayas region of Nepal has eight of the world's ten tallest mountains including the highest of all, Mount Everest at 8849 m. The Karakoram Range has four peaks over 8000 m including the world's second highest mountain, K2 at 8611 m. It also has the highest unclimbed mountain (as of late 2020) where climbing is not forbidden, Muchu Chhish at 7542 m.
For comparison, neither Western Europe nor the lower 48 US states have anything that reaches 5,000 m. In the Himalayan region, several of the passes are around 5000, and some nomads spend the summer at about that altitude every year so their herds can graze the upland meadows. Mount Elbrus is Europe's highest peak and Mount Kilimanjaro is Africa's; both are slightly under 6000 m. On the climbers' list of Seven Summits, the highest mountains on each continent, only two besides Everest are over 6000 — Denali in Alaska at just under 6200, and Aconcagua, the highest peak of the Andes and the tallest mountain outside the Greater Himalayan region, at just under 7000.
In the Himalayas, peaks over 6000 m are commonplace and there are dozens over 7000. Wikipedia's list of the highest mountains in the world consists entirely of 109 mountains in the greater Himalaya region, all over 7200 m (23,622 feet) and including 14 over 8000 m.
The Indian subcontinent and the rest of Asia are on different continental plates that are colliding; the Himalayas and related ranges are along the boundary of the plates. The force of the collision creates the world's highest mountains.
North of the Himalayas is the Tibetan Plateau, the world's largest and highest (over 3000 m on average) plateau. It includes all of Tibet and the Chinese province of Qinghai plus parts of several other provinces. A few centuries back, the Tibetan Empire covered approximately the same area as the plateau.
The ranges of the Greater Himalaya define several borders. The Himalaya proper is on the southern border of Tibet, hence the China-India border, and the China-Pakistan border is in the Karakoram Range. The western border of China runs approximately along the Tian Shan, while the Kunlun is the border between Xinjiang and the Tibetan Plateau; one branch of the Silk Road follows it on the north side.
The latitudes in the Himalayas range from almost tropical along the southern edge to about 40 north (latitude of Chicago, Beijing or Rome) in the Pamir Knot. However, Himalayan weather is more severe than in other places at similar latitudes, due to the altitude and the lack of any large body of water nearby to moderate the climate. Many of the peaks have snow atop them year round and there are many glaciers.
There is a large variation in micro-climates throughout the region; two valleys only a few miles apart but isolated by the mountains may have quite different climates because one gets more sun or they are affected differently by the wind patterns.
The diversity of wildlife in the Himalayas is huge. In the lower ranges, tigers, leopards, and the one-horned rhinoceros can be found while the higher altitudes support a smaller but more unique group of animals. These include the snow leopard, Markhor goat, argali, and red panda. Yaks are common as a domestic animal in much of the region.
The Himalayas are a home to a diverse number of people, languages, and religions. Generally speaking Islam is prevalent in the west, Hinduism along the southern edge, and Buddhism in the north. The eastern part of the Himalayas is ethnically diverse, with several tribal groups.
While there are numerous languages spoken, Hindi and Urdu will take you very far, as it is understood by the majority in the Pakistani and the Indian Himalayas. As the two languages are mutually intelligible in the spoken form, if you have to learn one before visiting, pick one of these. In Nepal, Hindi is not very useful, but it does have significant overlap with the Nepali language, and therefore gives you a head start with that language.
As a significant part of the Himalayas was under British rule, and even the nominally independent areas were under some form of British suzerainty, English is widely spoken by educated people. In the major tourist destinations, you will be able to get by with English with varying degrees of difficulty.
Most towns in the Himalayas can be reached by road, and some by train or plane, though many of the more rural areas require trekking and some of the trekking is quite difficult.
On the southern side most of the range can be reached via India, but western parts are reached via Pakistan or Afghanistan. Two small countries, Nepal and Bhutan, are located within the Himalayas on that side. On the north side, all of the Himalaya proper is in Tibet except for the small Indian trans-Himalaya region around Ladakh.
The Himalayas include the highest peaks on Earth and most sights relate to the mountains themselves, but because of the relative isolation of mountain valleys there is also an interesting diversity in flora, fauna and cultures. Some of the mountains are sacred to Muslims, Hindus or Buddhists and there are many monasteries, mostly Buddhist.
Trekking is the most popular activity, with a wide selection of possibilities, from deserts to jungles. It's also popular to study yoga or meditation. White water rafting is also popular in many places.
The Himalayas spread across several countries. All Himalayan regions offer similar attractions, but there are interesting differences as well.
A major tourist destination, with numerous sightseeing, trekking, and other adventure sport opportunities, Nepal has a level of tourist specific infrastructure far in advance of anywhere else in the region. Here you can trek for a month and stay in guest houses every night, and need not carry more than a change of clothes or two, and your sleeping bag. Nepal has unfortunately been suffering from a Revolutionary Maoist uprising making the country less than safe.
The Great Himalaya Trail is a trekking route that crosses Nepal east-to-west and goes near many of the world's highest mountains. It is a long-distance trek, 1700 km (over 1000 miles), and some of it is through difficult terrain.
A fascinating little kingdom, Bhutan only issues visas to tourists on expensive group tours or to individuals who benefit the country, such as NGO workers, or to exchange students.
The northern borders of India, Nepal and Bhutan generally follow the Ganges-Brahmanputra watershed, however the Himalaya extend north of this watershed. There are also outlying ranges rising out of the plateau northward to the Brahmaputra (or Yarlung Tsangpo as the river is called in Tibet) which are included with the Himalaya. This part of the Himalaya is less explored, often difficult of access, and has numerous unclimbed peaks.
A few centuries back, the Tibetan Empire was considerably larger than today's Tibet.
The old Tibetan province of Kham — now split up administratively between the two Chinese provinces Yunnan and Sichuan and China's Tibetan Autonomous Region — is closely related to Himalayan areas further west in both geography (large mountains created by the same tectonic plate collision) and people (predominantly Tibetan speakers). See Yunnan tourist trail for an overview and Tiger Leaping Gorge or Three parallel rivers for specific treks in the region. The famous scenic region of Jiuzhaigou in Sichuan was also part of Kham and named after nine Tibetan villages in the gorge, seven of which are still extant.
The Chinese province of Qinghai is also on the Tibetan Plateau. It was once Amdo province of the Tibetan Empire, and until the late 20th century its people were predominantly ethnic Tibetans. Today the Han (ethnic Chinese) are a majority, but they are mostly concentrated in the easternmost part of the province around Xining, while the rest of the province is sparsely populated and predominantly Tibetan.
If you are not planning to do any trekking, then you will not need any special equipment, or even warm clothing as you will be able to pick up good warm clothing on entry to the region. If you do need warm clothes, don't miss the second-hand markets selling attire from wealthy nations.
If you are trekking, the equipment you will need depends on your destination, in most of Nepal you will need nothing more than a sleeping bag and a pair of boots; the Indian Himalayas offer a large number of routes that are possible to trek independently if you have a tent, stove, and all the equipment needed for unsupported trekking.
In general the Himalayas have fewer dangers than the more densely populated plains around them.
Stay up to date with the news, and be willing to change your plans, when going to places such as Kashmir, that are facing armed uprisings.
Traffic on the narrow roads is often frightening, but due to the slow speeds is less likely to result in fatalities than on the roads of the plains.
Malaria is only an issue in the areas of low elevation, as the mosquito that carries the disease is not able to live at higher elevations. Take precautions when traveling through areas of lower elevation, especially the neighboring plains.
Altitude sickness is a worry, with many of the passes in the Himalaya being over 5000 m. Increase your elevation as slowly as possible, avoid flying from a low elevation to a high one, limit your physical activity; and drink lots of liquids after gaining altitude. Altitude sickness is unpredictable, and may strike people who haven't had problems before. Give yourself lots of flexibility in your plans, to avoid pushing yourself higher when you need to rest.
Flights out of the Himalayas are often cancelled due to bad weather, be sure to give yourself at least a few days before needing to catch a connecting flight.