Japan Standard Time or JST ( Nihon Hyōjunji or Chūō Hyōjunji) is the standard timezone of Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, and is 9 hours ahead of UTC

Coordinated Universal Time

Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...

. For example, when it is midnight (00:00) in UTC, it is 09:00 in Japan Standard Time. There is no daylight saving time

Daylight saving time

Daylight saving time —also summer time in several countries including in British English and European official terminology —is the practice of temporarily advancing clocks during the summertime so that afternoons have more daylight and mornings have less...

, though its introduction has been debated several times. Japan Standard Time is the same as Korea Standard Time

Korea Standard Time

Korea Standard Time is the standard time zone in North and South Korea and is 9 hours ahead of UTC : i.e., when it is midnight UTC, it is 9 am Korea Standard Time. Korea does not currently observe daylight saving time but has experimented with it in the past...

, Eastern Indonesia Standard Time

Time in Indonesia

The Indonesian archipelago geographically stretches across four time zones from UTC+7 in Banda Aceh to UTC+9 in Western Papua. However, The Indonesian government only recognizes three time zones in its territory: Western Indonesian Time—seven hours in advance of Greenwich Mean Time ,...

 and Yakutsk Time

Yakutsk Time

Yakutsk Time or YAKT, is a time zone in Russia, named after Yakutsk, the capital of the Sakha Republic. It is ten hours ahead of UTC and six hours ahead of Moscow Time .On 27 March 2011, Russia moved to year-round daylight saving time...

. During World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, it was often called Tokyo Standard Time in Western contexts.

History

Before the Meiji era

Meiji period

The , also known as the Meiji era, is a Japanese era which extended from September 1868 through July 1912. This period represents the first half of the Empire of Japan.- Meiji Restoration and the emperor :...

 (1868–1912), each local region had its own timezone in which noon was set to when the sun is exactly at its zenith. As modern transportation like trains were adopted, this practice started to cause confusion. For example, there is a difference of about 5 degrees in terms of longitude between Tokyo

Tokyo

, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...

 and Osaka

Osaka

is a city in the Kansai region of Japan's main island of Honshu, a designated city under the Local Autonomy Law, the capital city of Osaka Prefecture and also the biggest part of Keihanshin area, which is represented by three major cities of Japan, Kyoto, Osaka and Kobe...

 and because of this, a train that departed from Tokyo would arrive at Osaka 20 minutes ahead of the time in Tokyo. In 1886, Ordinance 51 was issued in response to this problem, which stated:

Ordinance 51 (on the precise calculation of time using the Prime Meridian) - July 13, 1886

• The prime meridian
  Prime Meridian
  The Prime Meridian is the meridian at which the longitude is defined to be 0°.The Prime Meridian and its opposite the 180th meridian , which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.An international...
  
   passes through England's Greenwich Observatory.
• Longitudes are calculated using the prime meridian, counting 180 degrees either east or west. Positive degrees are east, negative degrees are west.
• On January 1, 1888, 135 degrees east longitude will be set as the standard meridian for all of Japan, allowing precise times to be fixed.

According to this, the was set 9 hours ahead of GMT

Greenwich Mean Time

Greenwich Mean Time is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is arguably the same as Coordinated Universal Time and when this is viewed as a time zone the name Greenwich Mean Time is especially used by bodies connected with the United...

 (UTC had not been established yet). In the ordinance, the first clause mentions GMT, the second defines east longitude and west longitude and the third says the standard timezone would be in effect from 1888. Coincidentally, the city of Akashi

Akashi, Hyogo

is a city located in southern Hyōgo Prefecture, Japan, on the Seto Inland Sea west of Kobe.As of April 1, 2011, the city has an estimated population of 290,776, with 117,392 households, and a population density of 5,907.68 persons per km²...

 in Hyōgo Prefecture

Hyogo Prefecture

is a prefecture of Japan located in the Kansai region on Honshū island. The capital is Kobe.The prefecture's name was previously alternately spelled as Hiogo.- History :...

 is located exactly on 135 degrees east longitude and subsequently became known as Toki no machi (Town of Time).

With the annexation of Taiwan in 1895, Ordinance 167 (pictured on the right) was issued to rename the previous Standard Time to and establish new at 120° longitude. Western Standard Time, which was used in Taiwan and some parts of Okinawa, was abolished by ordinance 529 in 1937. Territories occupied by Japan during World War II, including Singapore

Singapore Standard Time

Singapore Standard Time or Singapore Time based in Singapore uses a time zone eight hours in advance of UTC .- History :...

 and Malaya

Malaysian Standard Time

Malaysia Standard Time or Waktu Piawai Malaysia or Malaysia Time is a standard time used in Malaysia. It is 8 hours ahead of Greenwich Mean Time and Coordinated Universal Time. The local mean time in Kuala Lumpur was originally GMT+06:46:48...

, adopted Japan Standard Time for the duration of their occupation, but reverted after Japan's surrender.

In 1948–1951 occupied Japan

Occupied Japan

At the end of World War II, Japan was occupied by the Allied Powers, led by the United States with contributions also from Australia, India, New Zealand and the United Kingdom. This foreign presence marked the first time in its history that the island nation had been occupied by a foreign power...

 observed daylight saving time

Daylight saving time

Daylight saving time —also summer time in several countries including in British English and European official terminology —is the practice of temporarily advancing clocks during the summertime so that afternoons have more daylight and mornings have less...

(DST) from the first Sunday in May at 02:00 to the second Saturday in September at 02:00, except that the 1949 spring-forward transition was the first Sunday in April. More recently there have been efforts to bring back DST in Japan, but so far this has not happened.