When do we use "at"?

We use "at" for a specific time or hour of the day, for example:

• at 10 AM -> I get up at 10 AM on Sundays.
• at midnight -> The fireworks appear at midnight on New Year's Eve.

"At" is also used for a holiday period or a festical, such as:

• at Christmas -> We always sing carols at Christmas.
• at Thanksgiving -> My aunts come and visit us at Thanksgiving.

When do we use "on"?

We use "on" for specific days, for example:

• on Monday -> I have a doctor's appointment on Monday.
• on Wednesday -> She always goes gorcery shopping on Wednesday.
• on Christmas Eve -> We had a huge holiday family dinner on Christmas Eve.

We also use "on" when talking about dates, for instance:

• on May 20th -> My brother celebrates his birthday on May 20th.
• on December 25th -> We always visit my grandparents on December 25th.

When do we use "in"?

The preposition "in" is used with months, for example:

• in February -> My birthday is in February.
• in September -> We are moving house in September.

The preposition "in" is also used with years, for example:

• in 1789 -> The French Revolution began in 1789.
• in 1992 -> I was born in 1992.

The preposition "in" is also used with decades, such as here:

• in the 1960s -> The Beatles were the most popular band in the 1960s.
• in the 1920s -> Many Western cities experienced a time of economic prosperity in the 1920s.

The preposition "in" is also used with centuries, such as:

• in the 17th century -> Louis XIV was a French king in the 17th century.
• in the 21st century -> We are living in the 21st century.

When talking about seasons, we also use the preposition "in". For example:

• in winter -> We love to go skiing in winter.
• in spring -> I love when all the flowers bloom in spring.

When talking about a period of time, we also use the preposition "in". For example:

• in four hours -> She completed the whole marathon in four hours.
• in 10 years -> She wants to travel the world in 10 years.

For parts of the day, we also use "in", such as:

• in the morning -> I always have a cup of coffee in the morning.
• in the evening -> She wants to go out for dinner in the evening.

Note that we say "at night" and not "in night". This is a special exception to the rule.

"At the weekend" or "on the weekend"?

The word weekend has either "at" or "on" as a preposition. Typically, in British English, people say "at the weekend" and in American English you will much more often hear "on the weekend".

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