What is it? This is the 2020 Grand National, the most famous jumps race in the world, which sees a maximum of 40 runners attempt 30 of the toughest obstacles in a four-mile-two-furlong marathon around Aintree. When is it? This year"s race takes place on Saturday April 4, 2020. What time does the race start? It will begin at its now traditional start time of 5.15pm (British Summer Time). Where is it? Aintree Racecourse, which has hosted the race since 1839. The racecourse is situated approximately six miles outside of Liverpool. What TV channel is it on? Having moved around BBC and Channel 4 in recent years, the Grand National will once again be shown on ITV. You will also be able to follow the action on Telegraph Sport"s live blog. Which horses are running? The final field of 40 runners is yet to be selected and will not be confirmed until a couple of days before the race, at which point four official reserves will also be chosen in the event of any late withdrawals. Step one in whittling the field down to 40 came on February 11 when the British Horseracing Authority"s handicapper assigned weights to all 105 horses holding entries for the race. The handicap system is designed to create as close a race as possible. Essentially, the better horses carry the most weight and the outsiders carry the least. Each horse has an OR (official rating) and this will largely determine the weight they carry. In theory, the handicap system aims to create a dead heat between all 40 horses. Imagine that. Unsurprisingly, double Grand National champion Tiger Roll was allocated top weight of 11st 10lb alongside his Gordon Elliott-trained stable companion Delta Work. Bristol de Mai will carry 11st 8lb and Native River 11st 6lb, with a range of horses then on 11st 2lb. Between the weights being assigned and the week of the race, owners and trainers will have the chance to withdraw entries if they are unhappy with the weight allocated or do not want their horse to run in the race for whatever reason. Then, on the Thursday before the Grand National - April 2 - the final 40-runner field (plus four reserves) will be confirmed. Who is going to win? One name will dominate proceedings: Tiger Roll. This year"s race is all about the horse who last year became the first to win back-to-back Grand Nationals since Red Rum in the 1970s. Should his participation be guaranteed, Tiger Roll will undoubtedly go off as one of the shortest-priced favourites in recent history. And with good reason. The Gordon Elliott-trained horse was a 4/1 winner last year, having triumphed at 10/1 the year before. If you"re looking for another horse to take an early plunge on, you could do worse than looking at last year"s Irish Grand National winner Burrows Saint, the imperious former Gold Cup winner Native River, or Magic Of Light, who finished second in the Grand National last year at massive odds of 66/1. What are the latest odds? The odds will fluctuate between now and the moment the race gets underway on April 4. But as of the morning of February 11 (before the weights were allocated), the market leaders were: Tiger Roll - 5/1 Burrows Saint, Native River, Magic Of Light - 16/1 Kimberlite Candy, Walk In The Mill, Le Breuil - 20/1 Elegant Escape, Potters Corner, Yala Enki - 25/1 What are some of the famous fences? The Aintree fences are not quite as perilous as they were once upon a time after a series of alterations. However, they are still the most notorious obstacles in the business and enough to make the palms of any jockey sweat. Becher"s Brook: The sixth and 22nd fence in the race may not be the biggest, but it"s difficulty comes from the fact the landing side is six to 10 inches lower than the take-off side. Named after Captain Martin Becher, a jockey who fell at this stage and hid in the brook to avoid injury. Foinavon: One of the smallest on the course, the seventh and 23rd fence is named after the 100/1 shot who avoided a disastrous pile-up here in 1967 and went on to win. Canal Turn: The eighth and 24th fence requires horses to take a sharp 90-degree turn upon landing over the 5ft obstacle. Aintree myth suggests that horses who refused to turn used to end up in the Leeds and Liverpool Canal. Valentine"s Brook: The ninth and 25th fence is named after a horse that allegedly jumped it backwards in 1840. More likely, the horse spun around in mid-air to create the optical illusion that its hind legs landed first. The Chair: Jumped only once, the 15th fence is the tallest on the course. It stands at 5ft 2in and is preceded by a 6ft-wide ditch. What happened during last year’s race? The 2019 Grand National saw Tiger Roll retain the trophy he had won a year earlier, beating Magic Of Light to make history as a back-to-back champion. You can read Telegraph racing correspondent Marcus Armytage"s full 2019 report here and below is a snippet: The spirit of Red Rum returned to Aintree on Saturday when Tiger Roll, the 4-1 favourite, became the first horse for 45 years to win the Randox Health Grand National two years in succession romping to a two and three quarter length victory in the spring sunshine at Aintree. The 172nd Grand National will go down in Aintree folklore as the one when Tiger Roll, racing’s rockstar, was admitted to one of the most exclusive clubs in sport: a two time winner of the world’s greatest race. Abd-El-Kader, The Colonel, The Lamb and Manifesto won twice in the 19th century when there were traditionally smaller fields but only Reynoldstown in 1935 and 1936, has joined that club in the last 100 years and Tiger Roll could now come back in 12 months’ time to try something even Red Rum could not manage; three in a row. Are there tickets left? The majority of areas are sold out, but there are still tickets available in the Garden Club, Festival Zone and The Embankment. Hospitality packages are also available. What are the other key dates? The Grand National serves as the culmination of three days of top-class racing at Aintree. Ladies Day takes place on Friday April 3, while Thursday April 2 is Liverpool"s Day.