"Yours faithfully" is used in formal situations to express a service to be rendered. For example, a lawyer will sign off like this. In England where there is ranking, it is also used by a subodinate to his superior. However in the US, this is considered archaic as it has the connotation of being a servant to another person. Hence, "Yours sincerely" is the preferred term in modern business letters etc.

You would use sincerely when a name of the reciever is mentioned at the beginning. faithfully when it's not.

Here are the British rules: 1. Opening: Dear Mr. Smith Closing: Yours sincerely 2. Opening: Dear Sir Closing: Yours faithfully No variations are allowed if you wish to be absolutely correct.

I believe this is British English. We have slightly different forms here in the U.S.

"Yours truly" etc as suggested by zaeanderson is more of a personalization with the recepient in a casual atmosphere. "Yours sincerely", "Yours faithfully" are used in formal situations to show professionalism. You don't use "Yours truly" when you write a cover letter. How can you be true when you have not set foot into the place yet. Just shows real insincerity. To be on the safe side, just stick to the accepted forms for that particular situation and don't try to be more "colorful". Your application, etc will be automatically thrown away before reaching the proper authority by the one who is ferreting out the good and the bad ones.