Internet self-classification codes are means of textually representing certain personal attributes to other members of common subcultures. The codes generally have a canonical definition which is periodically updated by individuals; no known standards bodies exist to regulate the codes.

Codes are typically expressed as a series of letters, numbers, and symbols, with each letter selecting some personal attribute, and the numbers and symbols expressing the degree or quality of that attribute in relation to the described individual.

In some parts of the net, it was once common practice to use a self-classification code in one's signature, though it is much less common now.