How many time zones are there in the world?

There are 24 primary time zones, but some regions use offsets of 30 or 45 minutes, bringing the practical total to over 30.

What is the difference between GMT and UTC?

They refer to the same baseline time. GMT is a time zone used in practice, while UTC is the international standard used for coordination.

No. Most countries do not observe daylight saving time. It is primarily used in parts of North America, Europe, and a few other regions.

Civil time zones sorted by GMT offset.

Time Zone	Abbreviation	GMT Offset	IANA Zone
Hawaii Time	HST	GMT-10	Pacific/Honolulu
Alaska Time	AKST / AKDT	GMT-8	America/Anchorage
Pacific Time	PST / PDT	GMT-7	America/Los_Angeles
Mountain Time	MST / MDT	GMT-6	America/Denver
Central Time	CST / CDT	GMT-5	America/Chicago
Eastern Time	EST / EDT	GMT-4	America/New_York
Atlantic Time	AST / ADT	GMT-3	America/Halifax
Brasilia Time	BRT	GMT-3	America/Sao_Paulo
Argentina Time	ART	GMT-3	America/Argentina/Buenos_Aires
Newfoundland Time	NST / NDT	GMT-2:30	America/St_Johns
UK Time	GMT / BST	GMT+1	Europe/London
West Africa Time	WAT	GMT+1	Africa/Lagos
Central European Time	CET / CEST	GMT+2	Europe/Paris
South Africa Time	SAST	GMT+2	Africa/Johannesburg
Central Africa Time	CAT	GMT+2	Africa/Harare
Eastern European Time	EET / EEST	GMT+3	Europe/Bucharest
Moscow Time	MSK	GMT+3	Europe/Moscow
East Africa Time	EAT	GMT+3	Africa/Nairobi
India Time	IST	GMT+5:30	Asia/Kolkata
Indochina Time	ICT	GMT+7	Asia/Bangkok
China Time	CST	GMT+8	Asia/Shanghai
Australian Western Time	AWST	GMT+8	Australia/Perth
Singapore Time	SGT	GMT+8	Asia/Singapore
Philippine Time	PHT	GMT+8	Asia/Manila
Japan Time	JST	GMT+9	Asia/Tokyo
Korea Time	KST	GMT+9	Asia/Seoul
Australian Central Time	ACST / ACDT	GMT+10:30	Australia/Adelaide
Australian Eastern Time	AEST / AEDT	GMT+11	Australia/Sydney
New Zealand Time	NZST / NZDT	GMT+13	Pacific/Auckland
Chatham Islands	CHAST / CHADT	GMT+13:45	Pacific/Chatham

How many time zones are there in the world?: There are 24 primary time zones, but some regions use offsets of 30 or 45 minutes, bringing the practical total to over 30.
What is the difference between GMT and UTC?: They refer to the same baseline time. GMT is a time zone used in practice, while UTC is the international standard used for coordination.
Do all countries observe daylight saving time?: No. Most countries do not observe daylight saving time. It is primarily used in parts of North America, Europe, and a few other regions.