Why do you write 'yours truly'?

Answer 1

It's a holdover from days of old, where people spoke - and wrote - in a staggeringly over the top formal style, in which undying protestations of eternal servitude were considered appropriate when dealing with any family, friend or acquaintenance.

Thus at the end of letters, they'd write things like, "Your most truly humble and sincerely obedient servant, Theodore Lawrence" or "Ever your most loyal and faithful servant, I remain your's in most sincere obedience, Arthur Pembroke" and the like.

"your's truly" is the contraction of all of that. Or even "your's", though most people leave off the possessive apostrophe (incorrectly, I might add). You'll also see "sincerely" by itself.

I've often wondered how today's texters would react to having to live in that era, where they never used one word when two dozen would do!

Answer 2

"Yours truly" is a common way to sign off at the end of a letter or message as a formal and polite expression of sincerity or respect. It is used to convey the writer's genuine intentions and to add a personal touch to the communication.

Answer 3

You use 'yours sincerely' when addressing some one you do not know - as in a job application. You use 'yours faithfully' when addressing some one you do know and are subordinate to them - such as your boss.

I might only be able to speak for the usage in England (where I am from) but I do not believe the above to be correct. We use "Yours sincerely" when we know the name of the recipient, e.g.

Dear Mr Smith

...

Yours sincerely

"Yours faithfully" is used when we do not know the name of the recipient, e.g.

Dear Sir/Madam

...

Yours faithfully

Both are only used in formal letters.