subject: When Did It Happen? In or On? [print this page] The English language can be trickyThe English language can be tricky. We have many pairs of words with similar meanings, e.g., Each and Every, Some and Few, and Much and Many. One pair that confuses many people is In and On when writing about when something happened. Although I see native English speakers make this mistake, I most often see it from people whose native language is other than English. Native English speakers typically use these words correctly because they are accustomed to hearing them used correctly. Not so for people who didnt grow up speaking English. Lets look at in and on and figure out which one to use. IN
Time can be divided into many types of time periods: months, years, days, hours, centuries, etc. Each time period has a beginning and an end. For example, if we write about the 20th century, we are writing about the time from January 1, 1900, to December 31, 1999. The century has a beginning and an end. If we write about the month of April, we are writing about the time beginning April 1 and ending April 30. During a time period, something occurs. The time period begins prior to the event and ends after the event. The event doesnt take up the entire time period. Rather than providing the exact date, we can refer to the time period. In these cases, we use the word IN to describe when the event occurred. For example, lets say the date of my birth was February 14, 1952. If I am writing about my birth, and I dont want to give the exact date, I might refer only to the year. So, during the time period January 1, 1952, to December 31, 1952, I was born. The year began before my birth and ended after my birth. In this case, I was born IN the year 1952. Im not writing the specific date; instead, I am referring to the time period during which my birth occurred. Heres another example. February 14th is Valentines Day. However, if I am writing about Valentines Day and I dont want to provide the exact date, I can write that Valentines Day occurs IN February. Valentines Day occurs during the time period called February, and Im not providing the exact date, so I write IN. ON
Whereas in describes a time period, on provides the exact date. When we write on, we are not describing the time period during which the event occurs. Instead, we are communicating the specific date. Using the examples above, I could write that I was born ON February 14, 1952. This is the specific date. Similarly, I could write that I was born on Valentines Day. This, too, refers to a specific day. Now lets look at the second example. When is Valentines Day? Valentines Day is February 14. That is the specific date ON which Valentines Day occurs. When we are writing about the date, we will use ON, as in Valentines Day is ON February 14. The Main Difference The main difference between IN and ON is this: In refers to a time period and is inexact. ON refers to a specific day and is exact. Thus, I was born IN 1952, and I was born ON February 14, 1952. A Joke to Help You Remember Two men, Bob and John, were talking about all the things they have done in their lives. Bob asked John, John, when was your birthday? John replied, My birthday was ON December 12.
No, said Bob. I mean IN what year was your birthday.
