Letter
A letter is a written message. Letters are usually intended to be received by someone far away. Before widespread availability of typewriters and computers, letters were always written by hand. Nowadays, that is still done, mainly for informal letters. The term letter is sometimes used for e-mail messages with a formal letter-like format.
A letter is also a character of an alphabet, abjad, or syllabary.
The letter is also a standard US paper size, measuring 8½×11 inches.