When you are writing a letter, the language you use and the layout of the letter will depend on how formal the letter is.

If you are writing a formal letter, such as a business letter or an application for a job, you use formal language, as in the example below.

You put your address in the top right-hand corner. You can put a comma at the end of each line, and a full stop at the end of the last one, but this is not necessary. Don't put your name above the address.

You put the date under your address. If you are using headed notepaper, you put the date above the address of the person you are writing to or at the right-hand side of the page. You can write the date in several different ways, for example 29.4.04, 29/4/04, 29 April 2004, or April 29th, 2004.

In American English the month is put in front of the day, for example 4/29/04.

You put the name or job title and the address of the person you are writing to on the left-hand side of the page, usually starting on the line below the date.

You begin a formal letter with the person's title and surname, for example Dear Mr Jenkins, Dear Mrs Carstairs, or Dear Miss Stephenson.

If you do not know whether the woman you are writing to is married or not, you can use the title Ms. If you are writing a very formal letter, or do not know the person's name, you use Dear Sir or Dear Madam. If you are not sure whether the person you are writing to is a man or a woman, it is safest to write Dear Sir or Madam.

When writing to a company, Dear Sirs is used in British English and Gentlemen in American English. It is also acceptable in American English to address a company as if it were a person when you do not have a name or person to send your letter to: Dear AT&T.

People writing in the formal American style put a colon after the 'Dear...' expression, for example Dear Mr. Jones:. If you are writing in the British style, you can either use a comma or have no punctuation.

If you begin the letter using the person's title and surname (for example Dear Mrs Carstairs), you finish with Yours sincerely. If you want to be less formal, you can finish with Yours. If you begin your letter with Dear Sir, Dear Madam, or Dear Sirs, you finish with Yours faithfully.

In American English, the usual way of finishing a letter is with the expression Sincerely yours or, more formally, Very truly yours. You write your signature underneath the expression you finish with. You can type your name (or write it in capitals) underneath your signature. If you are writing a business letter, you can also put your job title.

If you are writing a letter to a friend or relative, you use informal language, as in the example on the next page.

You put your address and the date, or just the date, in the top right-hand corner. Don't put the address of the person you are writing to at the top of the letter.

You normally begin an informal letter to a friend using Dear and the person's first name, for example Dear Louise. When people are writing to a relative, they use the person's 'relative' title, for example Dear Dad, Dear Grandpa, or Dear Grandma.

There are various ways in which you can end an informal letter. You can use Love or Lots of love when writing to close friends or relatives. When writing to someone you know less well, you can use Yours, Best wishes, or All the best.

The example below shows how to write the name and address on an envelope. In British English, some people put a comma at the end of each line, and a full stop after the county or country.

You usually use the title, initial or initials, and surname of the person you are writing to.

You can also use the person's title, first name, and surname: Miss Sarah Wilkins. When the letter is informal, you can just use their first name and surname, or their initial (or initials) and surname: Sarah Wilkins or S Wilkins.

If you are writing to someone who is temporarily staying with someone else or staying in a particular place, you put their name first and then, on the line below, put c/o in front of the name of the other person or the place, as in the example below. c/o stands for care of.

When sending a letter to a place in Britain, you should put the postcode (the set of letters and numbers at the end of the address) on a separate line. The American equivalent is a zip code, and needn't be on a separate line.