Time Zones around the World: Meaning, Types and Significance Explained

Time zones are defined by the imaginary lines that run from the north pole to the south pole. These imaginary lines are called longitudes. These lines divide earth into 24 time zones, each of which is approximately 15° wide. In the past, people used to tell time based on the position of the sun. However, the sun is not shining down on the whole planet at once. So, different parts of the earth receive sunlight at different times as it spins. If it is daytime in one part of the earth, it is night in the other. Different time zones ensure that noon i.e., 12:00 PM always happens when the sun is high in the sky right at 90° above earth no matter which part we are in. This means different parts will have different time zones. Explore how earth is divided into different time zones and how they work and linked to each other.

Table of Contents

• What Is a Time Zone?
• Why Do We Need Different Time Zones?
• Types of Time Zones

What is a Time Zone

A time zone in simple words is an area of the globe which follows a uniform clock time. This means everyone in one time zone agrees to set their clocks at the same time. For example, everywhere in India we follow the same time zone called Indian standard time or IST. Similarly, other countries of the world follow single or multiple time zones. For example, France is the country that follows the highest number of time zones. It has 12 different time zones. Let’s understand why we need them.

Why do we Need Different Time Zones

Time zones exist because the Earth is round and spins. This means two places on the globe can have day and night at the same time. Now imagine we want to contact our friend living in another country, so we call them in the afternoon but we accidentally wake them up at 3 AM in the morning as it's night time in that part of the world and. Time zones were created to avoid such mismatches. By understanding the time zones we can plan our travel and manage global dealing and understand global events easily. They allow us to manage business, transport, travel and communication between different parts of the world without disruptions.

Types of Time Zones

It takes earth exactly 24 hours to spin once around, which is 360 degrees. So to measure the width of each time zone scientists divide 360 degrees by 24 hours. 15 degrees is the width of each time zone and longitude is the imaginary line that divides the earth into those zones. When we travel globally towards the east direction, one hour gets added to each zone. When we travel west, time gets earlier, subtracting one hour per zone.

Time zones start from 0° longitude that divides the globe into the north and south hemisphere. It is the reference for standard time zones. This starting line running through the Royal Observatory in Greenwich, London is called prime meridian and is the anchor for all the world's clocks. UTC is the global reference of time which is the short for coordinated universal time. 

Each time zone adopts a fixed offsite from the UTC. For example, Indian standard time or IST zone is UTC+5:30. Although all 24 time zones differ from UTC by a full hour, some are there that are offset at 30 or 45 minutes just like IST. Based on this reference with UTC there are over 38 distinct time zones on earth. Here is a complete list of time zones:

This is how we calculate the standard time for the entire world using time zones. Today, the whole world follows this approach of standard time to relate with different time zones on the globe for trade, communication, financial deals, travel and more.