They are closings at the end of a letter
1. Yours sincerely
2. Sincerely
3. Sincerely yours
4. Faithfully yours
5. Faithfully
6. Truly yours
7. Truly
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I know that 'Sincerely' is used.
What about #5 and #7? Can they be used as closings? Are #2, #5, and #7 informal closings at the end of a letter?
I've seen 1, 2, 3, 6, 7, and some slight variations. These are quite commonly used.
I have not seen 4 and 5, but I think these would probably be used at the end of a love letter. They might be used in other circumstances, too.