Calendar

• A calendar is a system of organizing days for social, religious, commercial or administrative purposes. This is done by giving names to periods of time, typically days, weeks, months and years.
• A date is the designation of a single, specific day within such a system. A calendar is also a physical record (often paper) of such a system.
• A calendar can also mean a list of planned events, such as a court calendar or a partly or fully chronological list of documents, such as a calendar of wills.
• Periods in a calendar (such as years and months) are usually, though not necessarily, synchronised with the cycle of the sun or the moon.
• The most common type of pre-modern calendar was the lunisolar calendar, a lunar calendar that occasionally adds one intercalary month to remain synchronised with the solar year over the long term.

Calendar Systems:

Calendar Systems	Description
Lunar Calendars	1. Lunar calendars are synchronized to the motion of the Moon (lunar phases). 2. An example is the Islamic calendar.
Solar Calendars	1. Solar calendars are based on perceived seasonal changes synchronized to the apparent motion of the Sun. 2. An example is the Persian calendar.
Lunisolar Calendars	1. Lunisolar calendars are based on a combination of both solar and lunar reckonings. 2. Examples include the traditional calendar of China, the Hindu calendar in India, and the Hebrew calendar.

Calendars in Use:

Types of Calendar	Description
Gregorian Calendar	1. The Gregorian calendar is the de facto international standard, and is used almost everywhere in the world for civil purposes. 2. It is a purely solar calendar.
Religious Calendars	1. The most important use of pre-modern calendars is keeping track of religious feast days. 2. Eastern Christians use the Julian calendar. 3. The Islamic calendar, is a lunar calendar consisting of 12 lunar months. 4. Various Hindu calendars remain in use in the Indian subcontinent, including the Nepali calendar, Bengali calendar, Malayalam calendar, Tamil calendar, VikramaSamvat used in Northern India.
National Calendars	1. The Chinese, Hebrew, Hindu, and Julian calendars are widely used for religious and social purposes. 2. The Iranian (Persian) calendar is used in Iran and some parts of Afghanistan. 3. The Ethiopian calendar is the principal calendar used in Ethiopia.
Fiscal Calendars	1. A fiscal calendar generally means the accounting year of a government or a business. 2. It is used for budgeting, keeping accounts and taxation. It is a set of 12 months that may start at any date in a year. 3. The US government’s fiscal year starts on 1 October and ends on 30 September. The government of India’s fiscal year starts on 1 April and ends on 31 March. 4. Small traditional businesses in India start the fiscal year on Diwali festival and end the day before the next year’s Diwali festival.

Interesting Facts:

• The word calendar comes from the Latin word, ‘Calendae’, which means the first day of the month.
• Gregorian Calendar, the most commonly used calendar today, was introduced by Pope Gregory XIII.
• In the Julian calendar, every year divisible by 4 is a leap year. However, in the Gregorian calendar, there is an exception – century years are not leap years, unless divisible by 400.
• Before adopting the Gregorian calendar, the English new year was observed on Lady Day, March 25th, which celebrates the Virgin Mary.
• Gregorian calendar is a type of solar calendar, based on earth’s revolution.
• Calendars like the Islamic calendar are lunar calendars that are based on phases of the moon.
• Hebrew and Hindu calendars are types of lunisolar calendars which are based on movement of both, the Sun and the Moon.