[4][5]The first Isle of Man TT race was held on Tuesday 28 May 1907 and was named the International Auto-Cycle Tourist Trophy.

[6] The event was organised by the Auto-Cycle Club over 10 laps of the Isle of Man St John's Short Course of 15 miles 1,470 yards for road-legal 'touring' motorcycles with exhaust silencers, saddles, pedals and mudguards.

[10][11][12][13] The race is regarded as the most dangerous motorsport event in the world; The New York Times said in 2017 that the number of deaths had risen "to 146 since it was first run in 1907; if one includes fatal accidents occurring during the Manx Grand Prix ... the figure rises above 250".

"[16] In 1976, the Isle of Man TT lost its world championship status; this was transferred to the United Kingdom by the FIM and run as the British Grand Prix for the 1977 season.

The Classic TT brand ceased operation prior to the 2022 event, with classes for historic racing motorcycles integrated into the Manx Grand Prix.

[19] The coroner also noted that "I am more than aware of the fact that the witnesses from the Manx Motor Cycle Club and the marshals are all volunteers.

[21][22] Motor racing began on the Isle of Man in 1904 with the Gordon Bennett Eliminating Trial, restricted to touring automobiles.

The 1905 Gordon Bennett Trial was held on 30 May 1905 and was again won by Clifford Earl driving a Napier automobile in 6 hours and 6 minutes for six laps of the Highroads Course.

Campbell (Ariel) despite a fire during a pit stop[25] in 4 hours, 9 minutes and 36 seconds at an average race speed of 30.04 mph (48.34 km/h).

Entrants must also cite pre-filled documentation of completion of a UK driving licence or motorcycle certification, or a driver's licence from a comparable country that is recognised by UK comparable department of transportation standards and may withhold due to any pre race or post race suspensions.

The 1912 event was the first to limit the Junior TT to only 350 cc machines and this engine capacity prevailed until 1976, after which the category was dropped.

The 2015 specifications for entries into the Supersport TT race are: Minimum Weight 161 kg[29] The 2015 specifications for entries for the Superstock TT, an event for production based motorcycles racing with treaded road tyres, are based on the FIM Superstock Championship specifications, as follows: Minimum (Dry) Weight 170 kg[30] Supertwin TT 2022 saw the introduction of the supertwin race run over 3 laps on Wednesday the 8th of June, increased to 4 laps the following year.

[32] This proved to be the winning combination when Oliver Godfrey won the 1911 Senior TT race riding an Indian at an average speed of 47.63 mph (76.65 km/h).

Fitted with a six-speed belt drive[33] Charlie Collier riding a Matchless motorcycle finished second in the 1911 Senior TT race and was later disqualified for illegal refuelling.

During an early morning practice session for the 1911 Isle of Man TT races, Victor Surridge died after crashing his Rudge motorcycle at Glen Helen, the first death of a competitor on the Snaefell Mountain Course and the first death in the Isle of Man of a person in an automotive accident.

[37] The riders were little-known, but as the stars were barred from entering the class, it provided a stepping-stone for future-stars but resulted in less spectator-interest.

When previewing the impending re-introduction of a specification-controlled, roadster-based class in March 1967, David Dixon wrote: "lack of inter-make rivalry probably put the final nail in the coffin".

Selected riders have previous race experience and are first-aid trained, with machines carrying medical equipment that can assist in managing a casualty.

[56][57][58] On 30 May 2018, an experienced TT rider, Steve Mercer,[59][60] was seriously injured during a head-on collision with an official Course Car at Ballacrye.

The car, being driven at high speed,[61][62] was conveying police officers to officiate at the scene of a fatality involving Dan Kneen.

[63][64] Immediately after the accident the organisers changed their protocols, requiring that returning riders must be controlled by motorcycle-mounted travelling marshals to the front and rear.

[62][64][68][69] The ACU admitted liability for the accident, but instructed that any legal claim for compensation by Mercer must be filed in the Isle of Man.

[60][70][71] In 2019, it was reported that the driver of the car in the collision had quit after criticism that he exceeded a newly introduced speed limit recorded by a GPS tracking device when he drove to attend a fatality involving Chris Swallow at Ballaugh in August's Senior Classic TT.

Gary Thompson, Clerk of the Course and an ACU employee, had been criticised in 2018 for also fulfilling the role of Safety Officer; consequently a new incumbent was in place for 2019.

The 2001 Isle of Man TT races were cancelled because of the outbreak of foot-and-mouth disease in the UK in the spring and summer of 2001.

[77] In 2020, the Isle of Man Government lost an estimated £4.8 million of its annual projected revenue due to the cancellation of the TT races.

[79] Updated in June 2024[80] The Isle of Man TT was part of the FIM Motorcycle Grand Prix World Championship (now MotoGP) between 1949 and 1976.