Computer programming is commonly called coding, but what are codes and how are they used in computers? The coding unit begins with the building blocks of codes, which are symbols. These are universal in the environment, and include letters, numerals, punctuation, arithmetic operators, icons, emojis, gestures and pictorial signs. A code is simply a system of symbols.. Examples of codes are Braille, ASL, sets of fabric care symbols, map symbols, music notation, and football referees’ signals. A key is a translation of a code into everyday language. On a ma[p, the key is called the legend. Students create keys for their favorite emojis. Computers operate using binary code, which includes only two symbols, 0 and 1. When used to represent numbers, binary code is a base 2 number system. Other number systems common in computer work are base 8 and base 16. We normally use base 10, but there are other bases in common use, such as base 2 for measuring length and fluid volume, base 5 on the abacus and counting by tally marks and bases 12, 24 and 60 for time measurement. Students learn the binary system, and use it to translate their birthdates into binary. They then represent these binary numbers using LEDs of different colors, to represent 0 and 1.