Concept:Time zone:A time zone is a geographical area, that follows a consistent time standard for commercial, social, and legal purposes.Two types of time zone are GMT and IST.GMT:?The mean solar time at the Royal Observatory at Greenwich is known as Greenwich Mean Time (GMT).In London, it is measured at midnight.GMT is frequently used interchangeably with UTC in different countries.IST:In India, the longitude of 82½° E (82° 30'E) is treated as the standard meridian.The local time at this meridian is taken as the standard time for the whole country.It is known as the Indian Standard Time (IST).Explanation:Abu Dhabi and India time difference:As the earth rotates from west to east, those places east of Greenwich will be ahead of Greenwich time and those to the west will be behind it.The rate of difference can be calculated as follows.The earth rotates 360° in about 24 hours, which means 15° an hour or 1° in four minutes.Thus, when it is 12 noon at Greenwich, the time at 15° east of Greenwich will be 15 À” 4 = 60 minutes.1 hour ahead of Greenwich time, which means 1 p.m.But at 15° west of Greenwich, the time will be behind Greenwich time by one hour, i.e., it will be 11.00 a.m.Similarly, at 180°, it will be midnight when it is 12 noon at Greenwich.Calculation:According to this perspective, we can say that the Abu-Dhabi time zone=(GMT+4) and IST are 5:30 hours ahead of GMT. So, the difference between Abu Dhabi and the Indian time zone is 1 hour & 30 minutes.That means India is 1hour and 30 minutes ahead of the Abu-Dhabi time zone.Thus, An EVS teacher has a student from Abu Dhabi, in her class. The teacher has her online class scheduled at 10:00 AM (IST). The time will the student attend her online class from his home in Abu Dhabi is 8:30 AM.Additional InformationDifferent time zones of the world:There are at least two time zones in 23 nations.Because the North and South Poles have all lines of longitude.Antarctica and the Arctic technically have all time zones.There are 7 main time zones present in the world.These are Atlantic Standard Time (AST).Eastern Standard Time (EST).Central Standard Time (CST).Mountain Standard Time (MST).Pacific Standard Time (PST).Alaskan Standard Time (AKST).Hawaii-Aleutian Standard Time (HST).Samoa standard time (UTC-11).Chamorro Standard Time (UTC+10).