Although harking back to ancient times, the Olympic torch relay is a modern phenomenon which began in 1936. For each Olympic Games, a new torch is designed to carry the flame on a journey to the host city.
CLICKABLE Explore the torches below to find out more.
Berlin Summer 1936
The first torch relay was staged ahead of the Berlin Games. Designed by sculptor Walter Lemcke and manufactured by steel and armaments giant Freidrich Krupp, 3,840 torches were made for 3,331 runners.
Two separate fuses ensured they could re-ignite should the burning point fall away. They were stainless steel, 27cm long and weighed 450g.
London Summer 1948
The last time the Olympic Games and a torch relay were held in the UK was in 1948. That torch was designed by Ralph Lavers, a fan of classical architecture. He needed to create something inexpensive but well-crafted for a torch to travel across Europe ahead of the "Austerity Games". Two types were made - one aluminium, with hexamine/naphthalene tablets stacked up inside and one for the final stretch in the stadium with a magnesium flame in a stainless steel holder, to be seen in bright daylight.
Oslo Winter 1952
The first winter Olympic torch relay began not in Greece, but Morgedal, the Norwegian cradle of ski-jumping and slalom. Torches had been used for centuries in Norway for night skiing and the idea was to take a "torch greeting" to Oslo. Ninety-five torches had a 23cm handle under an arching oval collar. An arrow linking Morgedal and Oslo decorated them.
Helsinki Summer 1952
Only 22 torches were made, rather than a mass production of hundreds. Instead, there were 1,600 gas canisters made to fuel them. Men ran with the torch for a 1km stretch, women slightly less. The torches were passed between runners and swapped for one with a fresh canister after about 20 minutes.
A 600g silver top rested in a curly birch holder. They were given to Olympic and sports organisations after the Games.
Cortina D'Ampezzo Winter 1956
The Olympic flame for the winter Games in northern Italy was kindled at the Temple of Jupiter on the Capitol, one of Rome's seven hills. This was because Rome had just been chosen for the 1960 Summer Games. A tripod sent from Olympia was used.
The first torchbearer to carry it was Olympic runner Adolfo Consolini. Part of this relay was executed on roller skates.
Melbourne Summer 1956
Ralph Lavers' London design is credited with inspiring the Melbourne torches. Equestrian events were held in Stockholm so the torch travelled to Sweden and Australia. Down Under, the torch was diverted around floods and braved bumpy roads that threatened to extinguish the back-up miners' lights. The times estimated for runners to complete each mile varied as it went through the tropics and temperate climes. It reached Melbourne after being carried 20,470km by 3,118 runners.
Squaw Valley Winter 1960
Disney was put in charge of the pageantry at the Winter Games in California and one of its 'imagineers', John Hench, designed the torch. He stuck broadly to the London/Melbourne design.
As with the Oslo Games, the torch was again lit in the Norwegian village of Morgedal, in the cabin of Sondre Norheim, the pioneer of modern skiing.
Rome Summer 1960
The slim, fluted design of the bronzed aluminium 580g torch was based on those seen on ancient monuments. The relay travelled from Greece, following the course taken by the ancients when they founded colonies on Sicily and the Italian peninsular to create Magna Grecia.
Innsbruck Winter 1964
Former skier of the 1956 Winter Olympics, Joseph Rieder, used the torch to light the cauldron. The Games were marred by the deaths of two athletes during training and by a lack of snow.
Tokyo Summer 1964
The torch travelled by air, land and sea from Olympia to Tokyo. In Japan, the flame split along four routes before reuniting. Yoshinori Sakai, born in Hiroshima on 6 August, 1945, the day the atomic bomb dropped, was the final runner and lit the cauldron. When the torch entered the stadium, chrysanthemum perfume was released from sprayers under the spectator stands.
Grenoble Winter 1968
It was an eventful journey through France for the bronzed-steel torch. Its bearer crossed Le Puy de Sancy on all fours, floored by a severe early-January snowstorm. It was carried across Marseille's old port by a diver, holding the torch above the surface at arm's length, to prevent the flame going out.
Mexico City Summer 1968
The 3,000 whisk-like torches featured a 3-D Mexico '68 emblem on the flaming top. The relay followed the route of Christopher Columbus from Europe to the New World where, for the first time, the cauldron was lit by a woman, Enriqueta Basileo. The solid fuel mixture was unexpectedly volatile - some minor explosions occurred and runners were slightly burned.
Sapporo Winter 1972
The torch, carried in Japan only by young people aged 11-20, again split its journey to be seen by as many people as possible. The aluminium alloy, pan-like holder held a 55cm-long cylindrical burner. It was fashioned in the image of the Olympic cauldron by designer Munemichi Yanagi, famed for his butterfly stool.
Munich Summer 1972
Otl Aicher's widely-adopted sporting stickmen were a key design feature of the Games. The gas torch was made of nickel chromium steel in three parts - handle, plate and fire pipe screwed together.
It was tested for resilience to extreme weather - including with a hand-spray to simulate heavy rain.
But not for extreme heat - when temperatures hit 46C en route from Greece to Germany, special pressurised torches had to be used.
Innsbruck Winter 1976
Akin to the Munich design, this torch also featured 3-D Olympic rings and was used to light two cauldrons, symbolising the second visit of the Olympic Games to Innsbruck.
After Greece, it was flown to Vienna and taken through Austria on two routes through the north and the south of the country.
Montreal Summer 1976
'How will it look on TV?' was a major consideration for Georges Huel and Michel Dallaire. They designed a red-handled torch with black burner and a gold and black special presentation edition. The flame was for the first time carried by a laser beam via satellite from Athens to Ottowa. But the torch ran on the more-traditional olive oil. On 22 July the Olympic cauldron went out during a storm and was re-lit from the back-up flame.
Lake Placid Winter 1980
The design returned to the plate and handle look but for the first time the team of torchbearers was small, comprising 26 men and 26 women from each US state. They were sportsmen and women and those who excelled in other fields. They followed a route through the country from near the first English-speaking settlements, taking in historic sites.
Moscow Summer 1980
Different again from what had come before, the gold and silver torch had a cup on top of a burner and the handle was shielded by a protective screen.
Leningrad enterprises made 6,200 gas torches designed by Boris Tuchin. It was registered as a state invention of the USSR and given certificate number 729414.
Sarajevo Winter 1984
The torch made by the Japanese sports company Mizuno again had a platform and narrow burning tube, featuring the Olympic emblem. The relay took two routes across Yugoslavia. It was mapped out to cover each major area of a country that, five years later, would begin to break up.
Los Angeles Summer 1984
The torch was made from spun aluminium with a brass finish and a leather handle. It featured a picture of the Memorial Coliseum, the venue for the 1984 and 1932 LA Games.
But the relay was controversial as the US sold the right to run each kilometre of the relay to runners for $3,000, displeasing the Greeks. Two hours in to the relay, the USSR announced it would boycott the Games, in a reversal of the US-led boycott four years earlier. But this did not stop thousands lining the route of the torch.
Calgary Winter 1988
Relatively heavy at 1.7kgs, the torch was shaped like the landmark Calgary tower with a Canadian maplewood handle and steel-moulded aluminium burner. It was engraved with the Olympic motto Citius Altius Fortius - swifter, higher, stronger. Laser-engraved pictograms on the handle represented the 10 official Winter Olympic sports. The 88-day relay went from the east coast to Calgary, through the country's 10 provinces and two territories.
Seoul Summer 1988
The Korea Explosive Company Ltd made this brass, plastic and leather-handled torch in a design similar to its immediate predecessors. Traditional Korean graphics including two dragons symbolised the harmony of East and West. The torch covered a mammoth 22-day, 4,167.8km route, through 21 cities, carried by 1,467 torchbearers, with thousands of assistants and escorts.
Albertville Winter 1992
This stainless steel torch marked the start of the modern shapes and high-profile designers. The French chose Philippe Stark - internationally-renowned for his furniture, products and, a decade earlier, reworking the apartments of the French President Francoise Mitterrand.
Barcelona Summer 1992
Andre Ricard, an industrial designer from Barcelona, made a deliberately different torch that aimed to be "latin" in character. The relay passed through 652 centres with bicycle relays on the sparsely-populated runs. The cauldron was lit at Montjuic Olympic stadium by a flaming arrow shot from the bow of Paralympic archer Antonio Rebollo.
Lillehammer Winter 1994
For the first time, the Winter and Summer Games began to alternate every two years. This skinny torch was wind-tested to make sure it would stand up to being skied down the jump to light the cauldron at the opening ceremony at Lysgardsbakken. Again, a flame was lit in Mordegal, this time taken on a 12,000km relay. But the Greeks objected to that flame being combined with the one from Olympia - the Olympian fire eventually travelled to Lillehammer.
Atlanta Summer 1996
Malcolm Grear's design of a handful of reeds bound together with twine was inspired by ancient torches. Twenty-two aluminium reeds represented each Olympic Games. With a pecan-wood centre handle, it was the longest summer torch. Modifications were made after some reeds melted, the flame was hard to see and it went out on the Greek leg of the relay.
Nagano Winter 1998
This torch took inspiration from the traditional Japanese Taimatsu but also incorporated modern elements. It aimed to be more environmentally friendly, with clean-burning propane, and was made of aluminium. The top's hexagonal shape represented ice crystals and the outside was silver, to evoke winter.
British anti-landmine campaigner Chris Moon, who lost two limbs while deactivating mines in Mozambique, ran into the stadium with the torch at the opening ceremony.
Sydney Summer 2000
The Sydney Opera house, a boomerang's curves and Pacific Ocean blue inspired the design. Its three overlapping components also represent Earth, fire and water. After a 10-day Greek relay, it showcased Australia from Uluru to the Great Barrier Reef. Aboriginal sprinter Cathy Freeman lit the flame in the Olympic Stadium and went on to win the 400m.
Salt Lake City Winter 2002
Shaped like an icicle and fashioned from western USA silver and copper, the torch was designed to promote the Salt Lake Games' motto "Light the fire within". The flame burned through the glass top, as if through ice. Relatives of those killed in the 11 September attacks were among those who ran with the torch.
Athens Summer 2004
Greek industrial designer Andreas Varotsos looked back to the ancient roots of the Games with a magnesium and wooden torch shaped like an olive leaf. The torch relay spanned five continents and gave 260m people the chance to see the flame in their city. The design aimed to have flow - from the bearer's hand, to the flame, through the torch.
Turin Winter 2006
Italian car design firm Pininfarina turned an eye to the torch from its traditional work for car industry giants like Ferrari, Maserati, Rolls-Royce and Jaguar. The torch resembled a ski and was inspired by mountains, with the flame burning around the head. But it was the 'big mama' of torches, criticised for being too heavy for bearers at just under 2kg.
Beijing Summer 2008
The paper scroll shape of the torch and the "lucky" or "auspicious cloud" graphics commonly used in Chinese mythology were intended to portray harmony. And the torch was meant to symbolise a green, high-tech, people's Olympics. An ambitious, longest-ever torch relay was run across five continents and China, but it frequently drew protests.
Vancouver Winter 2010
The Canadian design came from transport manufacturer Bombardier and the Hudson's Bay Company. It was long, at 94.5cms, and towards heavy, at 1.6kg. Its shape was inspired by the fluid lines cut by skis in snow and by the Canadian landscape. The winter-white torch had a maple leaf cut-out. It featured the Games motto and the Vancouver 2010 logo - that of an Inukshuk - piles of stones formed into human shape by Inuit people.
London Summer 2012
With London hosting the Games for a third time, a three-sided torch has been created by design firm Barber Osgerby. Golden, and made of shaped sheets of aluminium alloy, each torch is perforated with 8,000 holes representing the 8,000 torchbearers taking part in the relay. At 80cm it is one of the tallest torches but also one of the lightest, weighing 800-850g including its central propane-butane burner. Its proportions will allow it to be carried easily by younger torchbearers.