After the initial rounds of auditions, successful contestants are narrowed down by the judges.
The act which receives the most public votes in each semi-final goes through to the final, with the second finalist being decided by the judges from the second and third most popular contestants.
The wildcard was Simon Cowell's golden buzzer Sarah Ikumu.
Korean War Veteran and Singing Chelsea Pensioner Colin Thackery won the thirteenth series in 2019.
Pianist, singer and comedian Jon Courtenay won the fourteenth series in 2020.