Bar codes are the machine-readable representation of information. Different bar and space patterns are used to represent different characters. Sets of these patterns are grouped together to form a "Symbology". There are different bar code symbology each having special characteristics and features. The symbologies are designed to meet the needs of specific application in industry. Code 93 barcode standard (also called as USS code 93, Code 9 of 3) is one of the popular barcode symbology useful for encoding the Electronic Components.

Code 93 is a variable length symbology that can encode the complete 128 ASCII character set. Code 93 provides added security as compared to other available barcode symbology. Code 93 bar code was designed to provide barcode with both higher density and security. The barcode software automates all the process of creating barcode labels. The symbology of the Code 93 character set consists of barcode symbols representing upper case letters, digits and special characters as:

• Letters – A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z
• Digits – 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
• Special Characters – $, ., -, /, +, % and space character

It is an alphanumeric, variable length symbology used primarily by Canada Post to encode supplementary delivery information.