Arthur Edward Jeune Collins was an English cricketer and soldier. He held, for 116 years, the record of highest score in cricket: as a 13-year-old schoolboy, he scored 628 not out over four afternoons
Collins on an 1899 postcard
In cricket, a batsman is not out if they come out to bat in an innings and have not been dismissed by the end of an innings. The batsman is also not out while their innings is still in progress.
The scoreboard at Lord's during the Test match between England and New Zealand in 2013, showing Trent Boult as the Not Out batsman at the end of New Zealand's second innings