Hexspeak was created by programmers who wanted a unique identifier with which to mark memory and/or data. Since they used hexadecimal notation, which uses the digits 0123456789ABCDEF, it was possible to create small words.
Hexspeak is mostly either 16 or 32 bits. Examples include deadbeef, baadfeed, baadf00d, c0edbabe and c001d00d.
A recent example of Hexspeak is cafebabe, embedded in the hexadecimal bytecode of Java applets.
See: