Cryptograms

A cryptogram is a type of puzzle which consists of a short piece of encrypted text. Generally the cipher used to encrypt the text is simple enough that cryptogram can be solved by hand. Frequently used are substitution ciphers where each letter is replaced by a different letter or number. To solve the puzzle, one must recover the original lettering. Though once used in more serious applications, they are now mainly printed for entertainment in newspapers and magazines.

Cryptograms are solved primarily by two methods. First, pattern recognition. The easiest to recognize are single-letter words, which generally can only be A or I (or, rarely, O). Then there are a limited number of two-letter words such as IN, IS, IT, TO, AN, AT, AS, WE, HE, US, etc. One trick in particular is to look for the common TH- words, i.e. THE, THAT, THEN, THEY, THERE, THEIR.

Secondly, the successful cryptogrammer will use letter frequency to help suss out a difficult puzzle. The twelve most frequently-used letters in the English language are ETAOIN SHRDL, in that order. The least common letters are JXQZ. If you notice a certain letter being used again in again in any given cryptogram, at a frequency much higher than any other letter, its a good bet that its unencrypted form will be one of the ETAOIN group.