There are three types of letter:

1) Formal Letter

2) Semi-Formal Letter

3) Informal Letter

Please check their definition and an approach to write their beginning and ending.

1) Formal Letter:

                   A formal letter is usually to a company or to someone you don’t know for-example a letter to a bank or an insurance company. You should write its beginning and ending as follows:

Dear Sir, OR Dear Madam OR Dear Sir/Madam,

— Body —

Yours Faithfully,

2) Semi-Formal Letter:

                  A semi-formal letter is usually to someone whom you know for-example a letter to landlord or a letter to an employer etc. You should write its beginning and ending as follows:

Dear Mr.Smith,

— Body —

Yours sincerely,

3) Informal Letter:

An informal letter is usually to a friend of yours. The beginning and ending of such a letter should be as follows:

Suppose you are writing a letter to John Smith OR Mary Jones. You should write as:

Dear John OR Dear Mary,

— Body —

Best Wishes OR Best Regards,

In such a letter, you will be using an informal language to address a person in contrast to the language used in the other two types of a letter.