What common terms are used to close letters or emails?

Answer 1

It depends on the relationship of the writer to the person to whom they are writing.

Some examples of formal or business closings could be:

Sincerely,

Thank you for your time, (if requesting or commenting on something)

Respectfully, (this is used when addressing persons of government, most especially)

More informal options are:

Yours,

Yours truly,

Sincerely yours,

With love,

With kind regards,

Respectfully yours,

Again, it depends entirely on the relationship and formality of the correspondence. Also, the correct term for the phrase that occurs before one's signature in a letter, if that is what you are referring specifically to, is Closing, or sometimes it is called a Conclusion.

Most etiquette books (Emily Post, Letitia Baldrige are the most commonly referenced authors/sources) have exhaustive sections on proper letter-writing forms of address and closings.