The Channel Tunnel (sometimes called the 'Chunnel') is an undersea tunnel linking northern France and southern England. It is operated by the company Eurotunnel, who also run a railway shuttle (Le Shuttle) between Calais and Folkestone, carrying passengers in cars, vans and other vehicles.
Eurostar is a totally separate company and is Eurotunnel's biggest customer, running high-speed passenger services through the Channel Tunnel between London and a number of cities on the continent, including Paris, Brussels, Lille, Lyon, Avignon and Marseille.
The Channel Tunnel is actually comprised of three tunnels: two rail tunnels, used for freight and passenger trains, and a service tunnel.
The Channel Tunnel is 50.45 km long or 31.5 miles. That's the equivalent of 169 Eiffel Towers stacked on top of each other.
37.9 km (23.5 miles) of the Channel Tunnel is under the English Channel, making it the world's longest undersea tunnel.
The idea of a tunnel under the Channel was first proposed in 1802 but construction wasn't started until 1988. It was completed in 1993, and Eurostar services started in November 1994.
The Chunnel runs between Calais in northern France and Folkestone in south Kent. Vehicle traffic for Le Shuttle gets on in Calais and gets off in Folkestone. Calais is about three hour's drive from Paris and Folkestone is about an hour and a half's drive from London.
Eurostar trains, which are passenger only, leave from St Pancras International station in London (some services also take on passengers in Ebbsfleet and Ashford in Kent) and go directly to the centre of Paris, Brussels and the other Eurostar destinations in Europe.
At its deepest, the tunnel is 75 metres (246 feet) below the sea level. That's the same as 107 baguettes balancing on top of each other.
The Chunnel is made of three separate tunnels running parallel to each other. One train tunnel running south (UK to France), one train tunnel running north (France to UK) and one service tunnel. All three tunnels were drilled below the sea bed, and link Coquelles in Pas-de-Calais to Folkestone in Kent.
On 25 August 1874, Captain Matthew Webb became the first person to swim across the Channel from England to France.
He first attempted the crossing on 12 August 1874, but had to give up due to strong winds and rough seas.
Undeterred, he tried for a second time 12 days later.
Escorted by three boats and covered in porpoise oil he reached Calais in 21 hours 45 minutes, despite challenging tides and a jellyfish sting.
On 31 July 2003, Felix Baumgartner jumped from a plane 9100 metres (30,000 feet) above Dover wearing a carbon wing and flew for 35.5 km (22 miles) at a top speed of 350 kph (220 mph).
Six minutes later in landed in France and became the first man to cross the channel in a wing suit.
He told the journalists shortly after landing "For the last 2,000 metres I could see the other side and I knew I was going to make it".
On 17 May 2007, the comedian Tim Fitz Higham became the first man to row across the Channel in... a bathtub. Tim first attempted this incredible challenge in 2004 but was forced to abandon when he was caught in a storm with force 6 winds.
Before attempting the crossing, Tim had to learn to row and trained with the Britain's Olympic rowing team.
Tim completed the gruelling journey in nine hours and six minutes. On his arrival, he told journalists "You can't fake rowing; you can either do it or you can't. It's exhausting. Because you're using so much energy, and every area of your body, your heart and lungs are working overtime."
On 12 March 2010, The One Show presenter Christine Bleakley water-skied across the English Channel and completed the 21-mile (34 km) stretch in just 100 minutes.
Despite being terrified by water and admitting she wasn't a strong swimmer She became the first person to water-ski across the world's busiest shipping lane.
She raised thousands of pounds for Sport Relief in the process and, after finishing the challenge, said "I can't believe I've actually done it. It was really tough."
On 28 May 2010, Jonathan Trappe crossed the Channel strapped to 54 industrial strength helium balloons.
Jonathan started his incredible journey from a field, near Ashford, and became the first cluster-balloonist to cross the English Channel.
The 36-year-old adventurer drifted in the air for four hours before landing in a French cabbage field narrowly escaping death after avoiding a power line.
After landing Mr Trappe, said: "The flight was outstanding, but it was a hell of a landing. I'm tremendously proud. It's an outstanding thing to do."
Foot passengers can travel with Eurostar, between our UK stations (London St Pancras International, Ebbsfleet International in north Kent, or Ashford International in south Kent) and our stations on the continent . People who want to travel with their own vehicle or on a coach can use the Eurotunnel Le Shuttle between Folkestone and Calais. Before travelling with either Eurostar or Eurotunnel you will need to go through security, border and ticket checks before going through the Tunnel.
It took just under six years and 13,000 workers to build the Channel Tunnel. The total cost came at an eye-watering £4.65 billion which would be the equivalent of £12 billion in today's money.
The Eurostar travels through the Channel Tunnel at a speed of 160 kilometers per hour (100 mph) although when the train is outside the tunnel it reaches speed of 300 kilometers per hour (186 mph).