When do you sign a letter "Yours sincerely"?

American usage: "Sincerely yours" is used for personal letters that are somewhat formal. Very informal personal letters may be signed "Fondly" or "With love" or something similar.

Business letters are usually signed "Yours truly". An acceptable variation is "Very truly yours", although that is not used very often. I have never seen an American business letter signed "Yours faithfully" or any variation of that.

You use Yours sincerely when you know the name of the person you are writing to and Yours faithfully when you don't know the name of the person you are writing too, therefore you sort of correct.

My teacher said that she remember this by remembering Silly Fool equals Sir Faithfully.

This didn't work for me but years of being a PA has!

KD

I was always told "yours faithfully" was for business where you were saying you would be faithful towards any dealings with the recipient, and "yours sincerely" was for personal acquaintances where you were saying you were sincere in what you told them.

i have taken a course of letter writing for 3 years, and the explanation of yours is mostly correct, ''yours sincerely'' is used when u know exactly who the recipient is, (ie. Dear Mr Smith), ''yours faithfully'' is used when u dont kw who's exactly the recipient is (ie. Dear Sirs)

when i write a formal letter to an unknown person

In America, 'Sincerely yours,' is more common, and appropriate to all correspondence, but especially so any business correspondence.

it doesn't really matter, but logically, the reverse makes more sense: you can be sincere with anyone, but are more likely to be faithful to someone you know

never heard that

sincerely is always appropriate as far as i am aware.

how about when you are sincere