Military time now is shown above in the four-digit 24-hour format the armed forces, aviation and hospitals use. The first two digits are the hour counted from 00 to 23, the last two are the minutes, and there is no AM or PM because every hour of the day has its own number. Underneath you will find the civilian equivalent and the spoken form, because reading military time and saying it are two different skills.
Reading the four digits
Military time is written as a single four-digit block: 0700 rather than 7:00 AM, 1930 rather than 7:30 PM. Hours below ten take a leading zero, which is why 8 in the morning is 0800 and not 800. After noon the count simply continues — 1300 is one in the afternoon, 2100 is nine at night. If you want the arithmetic done for you, the military time converter handles both directions, and the military time chart lists every hour.
Why there is no AM or PM
The whole point of the 24-hour clock is that a time can only mean one thing. A note saying "the briefing is at 7" is ambiguous; "the briefing is at 1900" is not. That single property is why the format spread from the military into aviation, medicine, rail timetables and computing — anywhere that a twelve-hour mistake is expensive. For coordinating across regions the same logic leads to Zulu time, which removes time-zone ambiguity as well.