These are the days of the week:

Days of the week are always written with a capital letter. They are usually used without a determiner.

I'll see you on Monday.

However, if you are referring generally to any day with a particular name, you put a in front of the day.

It is unlucky to cut your nails on a Friday.

If you want to say that something happened or will happen on a particular day of a particular week, especially when making a contrast with other days of that week, you put the in front of the day.

He died on the Friday and was buried on the Sunday.

We'll come and see you on the Sunday.**

Saturday and Sunday are often referred to as the weekend, and the other days as weekdays.

I went down and fetched her back at the weekend.

The Tower is open 9.30 to 6.00 on weekdays.

They are open weekdays and Saturday mornings.**

When people say that something happens during the week, they mean that it happens on weekdays, not on Saturday or Sunday.

I never have time for breakfast during the week.

A few days in the year have special names, for example:

These are the months of the year:

Months are always written with a capital letter. They are usually used without a determiner.

I wanted to leave in September.

In a date, months can be represented by a number. January is represented by 1, February by 2, and so on. You can use early, mid, and late to specify part of a month.

You can't use 'middle' like this, although you can use the middle of.

I should very much like to come to California in late September or early October.

We must have five copies by mid February.

By the middle of June the campaign already had more than 1000 members.

When you are speaking, you refer to a year before 2000 in two parts. For example, '1970' is said as nineteen seventy, and '1820' is said as eighteen twenty.

In the case of years ending in '00', you say the second part as hundred. For example, '1900' is said as nineteen hundred.

For years ending in '01' to '09', such as '1901', you can say, for example, nineteen oh one or nineteen hundred and one.

You refer to years between 2000 and 2009 as two thousand (2000) or two thousand and eight (2008), for example.

Years after 2009 are said as either two thousand and ten (2010), two thousand and eleven (2011), etc or as twenty ten (2010), twenty eleven (2011), etc.

To be more specific, for example in historical dates, AD is added before or after the numbers for years after Jesus is believed to have been born: '1650 AD', 'AD 1650', 'AD 1650-53', '1650-53 AD'. Some writers who prefer to avoid referring to religion use CE, which stands for 'the Common Era': '1650 CE'.

BC (which stands for 'Before Christ') is added after the numbers for years before Jesus is believed to have been born: '1500 BC', '12-1500 BC'. An alternative abbreviation that does not refer to religion is BCE, which stands for 'Before the Common Era': '800 BCE'.

When writing a date, you use a number to show which day of the month you are talking about. There are several different ways of writing a date:

If you want to give the year as well as the day and the month, you put it last.

I was born on December 15th, 1933.

You can write a date entirely in figures:

Americans put the month in front of the day when writing the date in figures, so the date above would be written 4/20/03 or 4.20.03.

This way of writing dates is often used for the date at the top of a letter, and for dates on forms. Dates within a piece of writing are not usually written entirely in figures.

You say the day as an ordinal number, even when it is written in figures as a cardinal number. Speakers of British English say the in front of the number. For example, 'April 20' is said as April the twentieth.

Speakers of American English usually say April twentieth.

When the month comes after the number, you use 'of' in front of the month. For example, '20 April' would be said as the twentieth of April.

You can omit the month when it is clear which month you are referring to.

So Monday will be the seventeenth.

Valentine's Day is on the fourteenth.

When you want to tell someone today's date, you use It's.

'What's the date?' – 'It's the twelfth.'

These are the four seasons of the year:

Seasons are sometimes written with a capital letter in British English, but it is more usual to use a lowercase letter. They are written with a lowercase letter in American English.

I was supposed to go last summer.

I think it's nice to get away in the autumn.

In American English, fall is usually used instead of 'autumn'.

They usually give a party in the fall and in the spring.

Springtime, summertime, and wintertime are also used to refer generally to particular times of year.

Note that there is no word 'autumntime'.

A decade is a period of ten years. A century is a period of a hundred years. Decades are usually thought of as starting with a year ending in zero and finishing with a year ending in nine. For example, the decade from 1960 to 1969 is referred to as the 1960s.

In the 1950s, synthetic hair was invented.

He wrote most of his poetry in the 1840s.

When you are talking about a decade in the twentieth century, you don't have to say the century. For example, you can refer to the 1920s as the 20s, the '20s, the twenties, or the Twenties.

...the depression of the twenties and thirties.

Most of it was done in the Seventies.

You can't refer to the first or second decade of a century in the way described above. Instead you can say, for example, the early 1800s or the early nineteenth century. Some people refer to the first decade of the twenty-first century as the noughties.

Centuries are considered by many people to start with a year ending in 00 and finish with a year ending in 99. Ordinals are used to refer to them. The first century was from 0AD to 99AD, the second century was 100AD to 199 AD, and so on, so the period 1800–1899AD was the nineteenth century and the current century is the twenty-first century (2000–2099 AD). Centuries can also be written using numbers: the 21st century.

This style of architecture was very popular in the eighteenth century.

That practice continued right through the 19th century.

Note that some people think that centuries start with a year ending in 01, so, for example, the twenty-first century is 2001-2100.

You can add BC or AD, or CE or BCE, after the name of a century.

The great age of Greek sport was the fifth century BC.

You can also refer to a century using the plural form of its first year. For example, you can refer to the eighteenth century as the 1700s or the seventeen hundreds.

The building goes back to the 1600s.

...furniture in the style of the early eighteen hundreds.

You can use early, mid, and late to specify part of a decade or century. Note that you can't use 'middle' like this, although you can use the middle of.

His most important writing was done in the late 1920s and early 1930s.

...the wars of the late nineteenth century.

In the mid 1970s forecasting techniques became more sophisticated.

The next major upset came in the middle of the nineteenth century.

You use particular prepositions when mentioning the day, date, or time of year of an event.

You use at with:

In American English you say on the weekend not 'at the weekend'.

You use in with:

You use on with:

In British English you say at the weekend not 'on the weekend'.

Note that American speakers sometimes omit 'on' with days and dates.

Can you come Tuesday?

To show that something happened at some time in a particular period, or throughout a period, you can use during or over.

There were 1.4 million enquiries during 1988 and 1989 alone.

More than 1,800 government soldiers were killed in fighting over Christmas.

You can show when something happens using the adverbs today, tomorrow, and yesterday.

One of my children emailed me today.

You can also use a noun phrase consisting of a word like last, this, or next combined with a word like week, year, or month. Don't use prepositions with these time expressions.

They're coming next week.

If you say that you did something the week before last, you mean that you did it in the week just before the week that has just passed.

Eileen went to visit friends made on a camping trip the year before last in Spain.

I saw her the Tuesday before last.

If you say that something happened a week ago last Tuesday, you mean that it happened exactly one week before the previous Tuesday.

If you say that you will do something the week after next, you mean that you will do it in the week after the week that comes next.

I was appointed a week ago last Friday.

He wants us to go the week after next.

In British English, if you say that something is going to happen Thursday week, you mean that it is going to happen exactly one week after the next Thursday.

'When will it open?' – 'Monday week.'

This construction is not used in American English, where you have to say a week from Thursday.

I'm leaving a week from Wednesday.

If you say that something will happen three weeks on Thursday, you mean that it will happen exactly three weeks after the next Thursday.

England's first game takes place five weeks on Sunday.

Time (for information on how to indicate an indefinite date)

If you want to show that you are referring to something that occurred or will occur on a particular day or in a particular period, you use -'s after a noun phrase referring to that day or period.

How many of you were at Tuesday's lecture?

...yesterday's triumphs.

...next week's game.

...one of this century's most controversial leaders.

You can use the name of a day or period of the year as a modifier if you are referring to a type of thing.

Some of the people in the Tuesday class had already done a ten or twelve hour day.

I had summer clothes and winter clothes.

Lee had spent the Christmas holidays at home.

When showing what season a day occurs in, you use the name of the season as a noun modifier. You can also use -'s with summer and winter.

...a clear spring morning.

...wet winter days.

...a summer's day.

If something happens regularly, you can say that it happens every day, every week, and so on.

I call my parents every Sunday.

Every weekend we went camping.

You can also use an adverb such as daily or monthly. This is more formal and less common.

It was suggested that we give each child an allowance yearly or monthly to cover all he or she spends.

If you want to say that something happens regularly on a particular day of the week, you can use on and the plural form of the day instead of using 'every' and the singular form of the day. You do this when you are simply saying when something happens, rather than emphasizing that it is a regular event.

He went there on Mondays and Fridays.

In American English, the 'on' is often omitted in this meaning.

My father came out to the farm Saturdays to help his father.

If something happens at intervals of two days, two weeks, and so on, you can say that it happens every other day, every other week, and so on.

We wrote every other day.

A less common way of showing an interval is to say that something happens on alternate days, in alternate weeks, and so on.

Just do some exercises on alternate days at first.

You can also indicate an interval by saying that something happens every two weeks, every three years, and so on.

The World Cup is held every four years.

Take two tablets every six hours.

You can also show that something happens regularly by saying that it happens, for example, once a week, once every six months, or twice a year.

The group met once a week..

...in areas where it only rains once every five or ten years.

You only have a meal three times a day.