Military Time

https://military.onlineclock.net/chart/

9:00 a.m.	0900 or 0900 hours	"Zero nine hundred hours"
5:00 p.m.	1700 or 1700 hours	"Seventeen hundred hours"

12:00 a.m. is usually referred to as both 0000 and 2400 hours. Clocks which can display Military Time, however, always display this time of day as 0000 (and not as 2400).