When in doubt, and lost in that doubt, the giant brains will even direct the feeble minded to the appropriate node.

A better response, quoted from wiki - In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f. For example, the decimal numeral 79, whose binary representation is 01001111, is 4F in hexadecimal (4 = 0100, F = 1111). IBM introduced the current hexadecimal system to the computing world; an earlier version, using the digits 0–9 and u–z, had been introduced in 1956, and had been used by the Bendix G-15 computer.

Well yeah, this is the basics. There are different systems of using hex. the wiki article seems to cover enough of em. lol