Here are 10 points on this big story:
Liz Truss's woes began when her showpiece tax-slashing policy sparked market chaos, forcing her into a series of humiliating U-turns.
The moves, aimed at reviving the UK economy, had divided her Conservative Party just 45 days after she was appointed.
Liz Truss's departure leaves the ruling Conservative Party badly damaged, languishing more than 30 points behind Labour in the polls after 12 1/2 years in power.
Her successor will become the party's fifth premier in less than seven years since the 2016 Brexit referendum ushered in a period of unprecedented chaos in British politics.
The outgoing prime minister announced that an election to choose her successor would be completed within the next week.
Among the front-runners to take over as UK PM is Rishi Sunak, whom Liz Truss defeated in this summer's elections.
Sunak, former Chancellor of the Exchequer, currently has odds of 13/8, according to Sky Bet.
If he wins, Rishi Sunak would be the first Indian-origin person to hold the UK Prime Minister's office.
Other contenders in the summer are also likely to be in the fray, including Penny Mordaunt, Kemi Badenoch and Tom Tugendhat.
Former Home Secretary Suella Braverman, who was sacked on Oct. 19, may also be in the running.
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