I have always wondered about the difference between a calendar day and just a regular day. The same applies to a calendar month.
What I learnt is that a calendar day must feature on the calendar. That may sound silly. Let me explain.
The distinction is used when it concerns a work day or a business day. For example, a day has 24 hours, but a work day may have seven to nine hours depending on how each organisation structures its required hours of work. On this basis, the same logic applies to a work week, for example five, six, or seven days, depending on how many days an employer demands from its staff.
So, a work week can be described as five days, but a calendar week implies Monday to Sunday, that is a representation of a normal week as it falls on the calendar. Important to note here is that if a Wednesday in the week is a public holiday, it is still part of the calendar week. However, that Wednesday would not be included in a work or business week.
Thus, a calendar month is all the days of the month from the 1st to 30th or 31st and a calendar year is 365 days – from 1 January too 31 December – expect in a leap year when it is 366 days.
Wikipedia suggest that in the western world, “We are guided by the Gregorian calendar. The Roman calendar was reformed by Julius Caesar in 45 BCE. … The Gregorian calendar was introduced as a refinement of the Julian calendar in 1582, and is today in worldwide use as the de facto calendar for secular purposes.
History.com records that, “In 1582, when Pope Gregory XIII introduced his Gregorian calendar, Europe adhered to the Julian calendar, first implemented by Julius Caesar in 46 B.C. Since the Roman emperor’s system miscalculated the length of the solar year by 11 minutes, the calendar had since fallen out of sync with the seasons.
www.history.com/news/6-things-you-may-not-know-about-the-gregorian-calendar
While researching about days etc, I found an interesting usage of calendaring which is a “Paper-finishing process in which damp paper passes through several heated rollers to give it a smooth and shiny finish. Most book and writing papers are calendared while newsprint is usually not.
http://www.businessdictionary.com/definition/calendaring.html