1. A numerical representation of what point in a day it is. Time is displayed in hours, followed by minutes, and then seconds. There are 24 hours in one day, 1,440 minutes in one day, and 86,400 seconds in one day.
An hour may be represented by a numerical value of 1 to 12 or 0100 to 2400. Several digital clocks and computers running Microsoft Windows display civilian time using hours of 1 to 12 and represent the time of day with AM or PM. Many Unix, Linux, and other clocks may use military time, which has no AM or PM and uses hours of 1 to 24. Below is a listing of Military time values and their conversions to Civilian time.
|12 AM||2400||12 PM||1200|
|1 AM||0100||1 PM||1300|
|2 AM||0200||2 PM||1400|
|3 AM||0300||3 PM||1500|
|4 AM||0400||4 PM||1600|
|5 AM||0500||5 PM||1700|
|6 AM||0600||6 PM||1800|
|7 AM||0700||7 PM||1900|
|8 AM||0800||8 PM||2000|
|9 AM||0900||9 PM||2100|
|10 AM||1000||10 PM||2200|
|11 AM||1100||11 PM||2300|
Minute and second
A minute is represented by numerical values of 00 to 59. There are 60 minutes in every hour and 60 seconds in every minute.
The world is broken into 24 separate time zones that are used to help determine the time in all areas of the world. GMT (Greenwich Mean Time) or UT (Universal Time) is a method of referencing the time differences across the world. The GMT or UT is centered in the middle of the time zone as 12:00. Any time zone to the left of this is -GMT or -UT and any time zone to the right of this is +GMT or +UT. Below is a listing of time zone abbreviations, time zone descriptions, and the UT difference.
|Time Zone||Time Zone Description||UT|
|ACDT||Australia Central Daylight Time||UT +10:30|
|ACST||Australia Central Standard Time||UT +9:30|
|ADT||Atlantic Daylight Time||UT-3:00|
|AKDT||Alaskan Time Zone||UT-9:00|
|AST||Atlantic Standard Time||UT-4:00|
|AWST||Australia Western Standard Time||UT+8:00|
|BST||British Summer Time||UT+1:00|
|BST||Brazil Standard Time||UT-3:00|
|CAT||Central Africa Time||UT+2:00|
|CCT||China Coast Time||UT+8:00|
|CDT||Central Daylight Time (USA)||UT-5:00|
|CDT||Central Daylight Time (Australia)||UT+10:30|
|CEST||Central Europe Summer Time||UT+2:00|
|CET||Central Europe Time||UT+1:00|
|CKT||Cook Islands Time||UT-10:00|
|CLST||Chile Summer Time||UT-3:00|
|CST||Central Standard Time (USA)||UT-6:00|
|CST||Central Standard Time (Australia)||UT+9:30|
|CST||Cuba Standard Time||UT-4:00|
|CUT||Coordinated Universal Time||-|
|ECT||Eastern Caribbean Time||UT-4:00|
|EST||Eastern Standard Time (USA)||UT-5:00|
|EST||Eastern Standard Time (Australia)||UT+10:00|
|EST||Eastern Brazil Standard Time||UT-3:00|
|FST||French Summer Time||UT-2:00|
|GMT||Greenwich Mean Time||-|
|GST||Guam Standard Time||UT+10:00|
|GST||Gulf Standard Time||UT+4:00|
|GST||Greenland Standard Time||UT-3:00|
|GT||Greenwich Mean Time||-|
|HFE||Heure Francais d'Ete||UT+2:00|
|HST||Hawaiian Standard Time||UT-10:00|
|IST||Irish Summer Time||UT+1:00|
|IST||Israeli Standard Time||UT+2:00|
|IST||Iran Standard Time||UT+3:30|
|IST||Indian Standard Time||UT+5:30|
|JST||Japan Standard Time||UT+9:00|
|KDT||Korean Daylight Time||UT+10:00|
|KST||Korean Standard Time||UT+9:00|
|LST||Local Sidereal Time||-|
|MDT||Mountain Daylight Time (USA)||UT-6:00|
|MST||Mountain Standard Time||UT -7:00|
|MPT||North Mariana Islands Time||UT+10:00|
|MSD||Moscow Summer Time||UT+4:00|
|NST||North Sumatra Time||UT+6:30|
|PDT||Pacific Daylight Time (USA)||UT-7:00|
|PMT||Pierre and Miquelon Standard Time||UT-3:00|
|PST||Pacific Standard Time (USA)||UT-8:00|
|PST||Pakistan Standard Time||UT+5:00|
|SST||Swedish Summer Time||UT+2:00|
|SST||Singapore Standard Time||UT+8:00|
|TST||Turkish Standard Time||UT+3:00|
|WST||Western Standard Time (Australia)||UT+8:00|
|WST||Western Brazil Standard Time||UT-4:00|
|WST||West Samoa Time||UT-11:00|
Daylight saving time and summer time
Daylight Saving Time, or DST for short, is a period of time where, in most parts of the United States and other parts of the world, time gains or loses an hour on a specific date. DST is still being used today as a means to help conserve energy. As of 2007, in the United States, DST is observed from the second Sunday in March until the first Sunday in November.
Other countries have a "summer time", but do not change their clock time. For example, the European Union observes "summer time" from the last Sunday in March to the last Sunday in October.
Additional questions related to time
At what point does the time change from AM to PM?
AM changes to PM and PM changes to AM at the stroke of 12:00.
How does the computer store the time and date on a computer?
Every computer has a CMOS battery in the computer that keeps a small charge in the computer allowing it to maintain the time, date, and other system settings while the computer is off.
Also see: <time>, A.M., Access time, Connect time, Date, Deceleration time, Disk access time, Downtime, Epoch, Holdup time, Idle time, Link time, Measurement, NTP, P.M., Real-time, Recovery time, Response time, Run time, Seek time, Settling time, Tick, Time server, Time out, Time sharing, Time-slice, Time stamp, Timer, Transfer time, Universal time, Uptime