US-ASCII, the American Standard Code for Information Interchange, was developed during the 1960s and became the character set most commonly used in the United States for several decades thereafter.

US-ASCII uses 7 bits per character, so it can represent 2⁷ = 128 distinct characters. The first 32 US-ASCII characters are control characters such as the carriage return and tab characters, and character code 127 is used to represent a DEL (delete) character, so there are only 95 printable characters (including space but not including tab and other control characters).

The printable characters of US-ASCII include the 26 letters of the English alphabet in both upper case (capitalized) and lower case, the ten decimal digits, several punctuation marks such as period and comma, and a few other symbols such as the dollar sign. US-ASCII does not include a character for any currencies other than the dollar, and does not include the characters needed by European alphabets other than English.