Last year Chris Froome became the first British rider to win two Tours de France.This year he is aiming to join an elite club of seven riders to win three. Spain's Alberto Contador, who is also chasing a third win, Colombian Nairo Quintana, Italy's Fabio Aru and Australian Richie Porte were among the pre-race favourites.
Froome's Team Sky team-mate Geraint Thomas will be doing his utmost to help his fellow Briton and has given BBC Sport his guide to the three-week race.
The 21 stages of the 2016 Tour comprise nine flat stages, one hilly stage, nine mountain stages - including four summit finishes - and two individual time trials.
Saturday, 2 July - Stage 1: Mont-Saint-Michel - Utah Beach, 188km (116.8 miles)Winner: Mark Cavendish (GB/Dimension Data)
Report: Cavendish wins to wear yellow for first time
Mark Cavendish produced a sensational sprint to claim his 27th Tour de France stage win and put himself in the yellow jersey for the first time. Coastal cross-winds did not create too much havoc on a day when one of the race favourites Alberto Contador crashed heavily but escaped with bruises. Defending champion Chris Froome was anonymous for much of the day which is just how he would have wanted it.
Sunday, 3 July - Stage 2: Saint-Lo - Cherbourg-en-Cotentin, 183km (113.7 miles)Report: Sagan claims first yellow jersey with stage win
A solo break by Jasper Stuyven came within 500m of producing an upset but he was caught with the finish line in sight. Peter Sagan battled with Julian Alaphilippe on the run-in and the Slovak world champion emerged victorious, although he didn't initially realise he had won the stage. Chris Froome and Nairo Quintana finish together but Alberto Contador and Richie Porte lose time.
Monday, 4 July - Stage 3: Granville - Angers, 223.5km (138.9 miles)Thomas' view: "It's going to be the same as stage one. Expect a breakaway to go away, be controlled by the peloton and reeled in around 10-15km from the finish with a bunch sprint finish in Angers. The usual contenders such as Mark Cavendish, Andre Greipel and Marcel Kittel will battle it out. This is a mentally tough day, where a strong team is useful. At Team Sky we will try keep Luke Rowe and Ian Stannard fresh for the final 50km because they are good at fighting for position. They will shelter Chris Froome from any wind and if there is a technical run-in, with roundabouts or sharp turns, guide him to the finish. Losing 10 seconds on a stage like this may not sound like a lot but do it a few times and that's a minute gone and could be the difference between winning and losing the overall race."
Thomas' one to watch: "Andre Greipel. The 'Gorilla' has won 10 Tour stages and took the German national title last weekend, and his Lotto-Soudal team have built a squad around him."
Mark Cavendish will be looking to move joint second on the all-time list of most Tour stage wins. A victory in Angers would see him move level with French legend Bernard Hinault on 28, with just Eddy Merckx of Belgium ahead on 34.
You can follow Cavendish's progress from 12:00 BST with the BBC Sport website's live text commentary.
Tuesday, 5 July - Stage 4: Saumur - Limoges, 237.5km (147.6 miles)Thomas' view: "There is a chance of crosswinds that can split the peloton as we head south across the flat lands. The worst days are when it's windy but not windy enough to split the group and it's just stressful and fast all day. It's sometimes better to split and be in a smaller group. And even if there isn't any wind, it's still the first week of the Tour and that means it will still be stressful."
Thomas' one to watch: "Marcel Kittel. The German didn't ride in last year's Tour but won four stages in 2013 and four more in 2014. He may already have a couple of stage wins by now but his Etixx-QuickStep team has other ambitions with general classification rider Dan Martin and time-trial specialist Tony Martin."
Wednesday, 6 July - Stage 5: Limoges - Le Lioran, 213.5km (132.7 miles)Thomas' view: "This is a tough last 50km and has a bit of a one-day classics feel. It's the first time we hit the hills and, while they are not the proper big climbs, it might be a shock to the system for some. It looks like the sort of stage Peter Sagan could do well on but it depends whether his Tinkoff team ride for him because they have other ambitions with Alberto Contador having targeted a third Tour win."
Thomas' one to watch: "Alejandro Valverde. A breakaway may succeed but if not the finish will suit a punchy rider - one who can get over hills with a good turn of speed - such as the Spaniard who rides for Movistar."
Thursday, 7 July - Stage 6: Arpajon-sur-Cere - Montauban, 190.5km (118.4 miles)Thomas' view: "It may look a little lumpy but this is a stage for the sprinters because it's their final chance for a while with us heading into the Pyrenees mountains."
Thomas' one to watch: "Mark Cavendish. It could be any of the main sprinters but if he's not tasted victory yet, he will want to do so before the race hits the mountains."
Friday, 8 July - Stage 7: L'Isle-Jourdain - Lac de Payolle, 162.5km (101 miles)Thomas' view: "I can't see too many of the favourites for the general classification being too aggressive because the next two days are tough. The ascent of the Col d'Aspin will lead to a selection going over the top together but not necessarily the best riders. They will be a bit nervous because of the descent to the finish. All the top guys can descend the same when they are together but downhill runs to the finish cause a bit more stress because they can be dangerous."
Thomas' one to watch: "Steve Cummings. The Briton rides for the same Dimension Data team as Mark Cavendish. A breakaway has a chance of succeeding and he is the king of the breakaways - as he proved at last year's race."
Saturday, 9 July - Stage 8: Pau - Bagneres-de-Luchon, 183km (113.7 miles)Thomas' view: "We've been to see some of the finishing descents but we've done nothing special. Going downhill is part of bike racing and I don't think these two days of descents to the finish will cost you the Tour unless you make a big mistake. I don't think the race will be blown apart today, although it will be tough with four climbs."
Thomas' one to watch: "Thibaut Pinot. The Frenchman is among the best when the road starts going up. His time-trialling skills have improved but he probably needs to make up time in the mountains to keep in touch."
Sunday, 10 July - Stage 9: Vielha Val d'Aran - Andorre Arcalis, 184.5km (114.6 miles)Thomas' view: "Everyone will be warming up on the rollers because we begin with a climb and that's not the nicest way to start a day. We've been to see the last 60km of this stage and ridden the final three ascents and they are tough. It will be the first day where we get a really good look at the general classification riders."
Thomas' one to watch: "Chris Froome. Psychologically, it would be great if he could win the stage, or gain time on his rivals on the first big summit finish."
Monday, 11 July - Rest day
Tuesday, 12 July - Stage 10: Escaldes-Engordany - Revel, 197km (122.4 miles)Thomas' view: "After a rest day, the next day can be pretty bad and we are again starting with a big uphill slog. There will certainly be a strong breakaway group and then it's a case of whether the sprinters teams want to chase them down because the climb near the end may put them off."
Thomas' one to watch: "Michael Matthews. His Orica Green Edge team may decide to ride for him but they have several options, with the likes of Daryl Impey and Simon Gerrans in the squad."
Wednesday, 13 July - Stage 11: Carcassonne - Montpellier, 162.5km (100.1 miles)Thomas' view: "With two big stages for the general classification riders following this one, I'm willing to put a lot of money on this being a day for the sprinters. The likes of Chris Froome, Alberto Contador, Nairo Quintana and Fabio Aru will be sheltering in the peloton all day."
Thomas' one to watch: "Mark Cavendish. He won in Montpellier in 2011. He has the Olympics coming up but he starts the race with 26 stage wins, just two behind Bernard Hinault, who is second on the all-time list with 28. Eddy Merckx has won the most with 34."
Thursday, 14 July - Stage 12: Montpellier - Mont Ventoux, 184km (114.3 miles)Thomas' view: "It's Bastille Day and that means one thing: a lot of fighting amongst the French riders to get in the break. Not that the break will stay away because the general classification riders will come to the fore on the legendary ascent of Mont Ventoux. Hopefully I'll be feeling good and going well and be one of the last guys in front of Chris Froome, who will be setting the pace - assuming he's got the yellow jersey at this stage. I want to be controlling my effort, in case their are attacks that I need to follow, and not necessarily riding until I blow. If I'm still up there on GC, then I will keep fighting, but if I'm not, once my job is done, I'll sit up and save as much as I can for the next day."
Thomas' one to watch: "Nairo Quintana. The climbing specialist finished second both times Froome won the race. With a big time-trial day to follow, Froome may gauge his effort and try follow the Colombian if he attacks and hope to take time on other rivals."
Friday, 15 July - Stage 13: Individual time trial, Bourg-Saint-Andeol - La Caverne du Pont-D'Arc, 37.5km (23.3 miles)Thomas' view: "We went to recce this stage in November because it is a key day where lots of time can be gained and lost. You have to judge your effort well. There's no point going well on the first uphill section and then having nothing on the flat that follows. There's an uphill kick to the finish as well, so it will be an hour of suffering - which is at least better than six hours on the mountain stages. It's certainly leaning in Chris Froome's favour - the final 3km climb will help the other general classification guys but Froomey will be looking to put some time on his rivals."
Thomas' one to watch: "Tony Martin. It's tough to see past the German, who has won three world time-trial titles."
Saturday, 16 July - Stage 14: Montelimar - Villars-les-Dombes Parc des Oiseaux, 208.5km (129.6 miles)Thomas' view: "After two big general classification days, this is a day to recover as much as possible. There will be a strong breakaway group but it will probably come back together and end in a bunch sprint finish."
Thomas' one to watch: "John Degenkolb. The German was out injured early on in the year after being a hit by a car so it will be interesting to see if he has ridden himself into form and whether he can challenge four-time winner Peter Sagan for the green points jersey."
Sunday, 17 July - Stage 15: Bourg-en-Bresse - Culoz, 160km (99.4 miles)Thomas' view: "This will be one of the hardest days and not just because of the amount of climbing involved. The yellow jersey will be on the back of one of the favourites by now so nobody will be bothered about chasing those in the break. However, the make-up of the break is important - it could be smaller teams wanting a rider in there for added exposure, or riders chasing King of the Mountains points - so it could be hectic for the first hour until the right selection of riders are allowed to go clear."
Thomas' one to watch: "Romain Bardet. The Frenchman is expected to have a duel in the mountains with his compatriot Thibaut Pinot and if he has time to make up he may come to the fore."
Monday, 18 July - Stage 16: Moirans-en-Montagne - Berne, 209km (129.9 miles)Thomas' view: "This is the last chance for the sprinters before we get to Paris because four days in the Alps follow. But there is an uphill cobbled section at the finish in Berne and if Peter Sagan goes for it - or Swiss rider Fabian Cancellara - they could open up a couple of seconds on the rest of the field."
Thomas' one to watch: "Fabian Cancellara. It's his last Tour de France, he is in his home country and I'm sure he'll have a go to try and win his eighth Tour stage."
Tuesday, 19 July - Rest day
Wednesday, 20 July - Stage 17: Berne - Finhaut Emosson, 184km (114.3 miles)Thomas' view: "This is the first of a super hard four-day block and a big effort is needed at the end of a tough stage. A lot can change over these four days an,d even if a rider is a couple of minutes adrift, he can bring it back if the guy in the yellow jersey has a bad day and cracks."
Thomas' one to watch: "Nairo Quintana. He's always good in the back end of the Tour, certainly the ones he's done recently."
Thursday, 21 July - Stage 18: Individual time trial, Sallanches - Megeve, 17km (10.6 miles)Thomas' view: "We have been to see this stage and again it's a tough time trial and you need to be careful with your pace and effort. There could be big gaps if you go too hard at the bottom and lose you legs a couple of kilometres from the top."
Thomas' one to watch: "Richie Porte. The Australian is good at one-off time trials up a mountain. But it's stage 18 and who knows who will have the best legs. Any decent climber could have a good day. I don't think Chris Froome has any advantage - it's just riding up a hill as fast as you can."
Friday, 22 July - Stage 19: Albertville - Saint-Gervais Mont Blanc, 146km (90.7 miles)Thomas' view: "This is a dangerous stage. There will be a strong breakaway on that first climb and if the team of the yellow jersey wearer are having a bad day, their leader could easily be isolated, as happened to Chris Froome on stage nine in 2013. The leader might be strong enough to follow on a climb but if somebody goes on the flat it's harder. You could have the strongest guy in the race but if he's on his own early on it will tough for him to keep the jersey."
Thomas' one to watch: "Fabio Aru. The Italian won the Vuelta a Espana last year and has been chosen as Astana team leader over compatriot Vincenzo Nibali, who won this race in 2014. He is not as good a time-trial rider as the other favourites so may need to make up time in the mountains."
Saturday, 23 July - Stage 20: Megeve - Morzine, 146km (90.7 miles)Thomas' view: "These climbs were tough when we tried them after a training camp, so they will be even more punishing on stage 20 of the Tour de France. If we need to make time up, we'll make the stage as hard as we can for as long as we can. The descent into Morzine is not super-technical but it is the final descent in the Alps, in the Tour, and if you are tired and chasing hard, you could make a mistake, which makes it dangerous."
Thomas' one to watch: "Alberto Contador. If the two-time Tour winner needs to make up time on the race leader, he could go all in, attack super early and put everyone under pressure."
Thomas' view: "We finish with the traditional procession into Paris and a sprint finish on the Champs-Elysees. It's an amazing feeling to ride into Paris regardless of whether or not you are on the winning team. Obviously it's better if your lead rider has won because all the other riders are complimentary and it was incredible to finish arm-in-arm like we did last year. In 2014 it was a very different feeling because we didn't win. It was a bit strange because we had nothing to ride for, but you are still happy to complete the race, see your wife and friends, have a normal life, drink a beer and eat a pizza. Come the Sunday night, whether we have won or not, we will let off a bit of steam."
Thomas' one to watch: "Marcel Kittel. The German has won both the sprints he has contested on the Champs-Elysees, in 2013 and 2014. Andre Greipel won last year's sprint, while Mark Cavendish won four on the trot between 2009 and 2012."
The jerseysYellow jersey - worn by the overall leader of the race.
Green jersey - worn by the leader of the points classification. Points are awarded at intermediate sprints and the finish line for the first 15 riders. The winner of a flat stage picks up 50 points, sliding down to one for 15th. There are 30 points for the winner of medium mountain stage and 20 for a big mountain stage. Intermediate sprint winners pick up 20 points.
Polka dot jersey - worn by the leader of the King of the Mountains classification. Points are awarded at the top of categorised climbs. The number of points is doubled on a summit finish.
The first rider to reach the summit on the hardest category climbs is awarded 25 points, sliding down to two for the 10th rider. On category one climbs, the points slide from 10 to one for the first six riders. On category two ascents, the points are five, three, two and one for the first four over the line. Category three passes reward the first two to the top with two and one points, while one point is on offer for the first rider on a category four climb.
Points awarded are doubled on the summit finishes on the ninth, 12th, 17th and 19th stages.