World Clock

What are Time Zones?

Time zones are regions of the Earth that observe a uniform standard time for legal, commercial, and social purposes. They generally follow the boundaries of countries and their subdivisions rather than strictly following longitude, though they are roughly based on lines of longitude (each time zone covers approximately 15 degrees). The world is divided into 24 primary time zones, each offset from Coordinated Universal Time (UTC) by a whole number of hours.

Time zones exist because the Earth rotates on its axis, meaning different parts of the world experience daylight and darkness at different times. Before time zones were established in the 19th century, each city used local solar time, which caused significant confusion for railways and telegraph communications. The introduction of standard time zones revolutionized scheduling and coordination across long distances.

Major Time Zones Around the World

UTC (Coordinated Universal Time) is the primary time standard by which the world regulates clocks and time. Major time zones include EST (UTC-5, Eastern Standard Time) covering the US East Coast, PST (UTC-8, Pacific Standard Time) for the US West Coast, CET (UTC+1, Central European Time) for much of Europe, and JST (UTC+9, Japan Standard Time) for Japan and Korea.

Some countries use half-hour or even quarter-hour offsets. India uses UTC+5:30, Nepal uses UTC+5:45, and parts of Australia use UTC+9:30 and UTC+10:30. Daylight Saving Time (DST) adds further complexity by shifting some regions forward by one hour during summer months. This world clock automatically accounts for DST and all timezone offsets using your browser’s built-in timezone database.