i see alot lot: a hacker is this...no thats a cracker..oh no, no, no. a hacker is...

so here's the definition:

hacker /n./ [originally, someone who makes furniture with an axe]

A person who enjoys exploring the details of programmable systems and how to stretch their capabilities, as opposed to most users, who prefer to learn only the minimum necessary.

One who programs enthusiastically (even obsessively) or who enjoys programming rather than just theorizing about programming.

A person capable of appreciating hack value (the value of a seemingly worthless, but artistic/technical goal).

A person who is good at programming quickly.

An expert at a particular program, or one who frequently does work using it or on it; as in `a Unix hacker'. (Definitions 1 through 5 are correlated, and people who fit them congregate.)
An expert or enthusiast of any kind. One might be an astronomy hacker, for example.

One who enjoys the intellectual challenge of creatively overcoming or circumventing limitations.

[deprecated] A malicious meddler who tries to discover sensitive information by poking around. Hence `password hacker', `network hacker'. The correct term for this sense is cracker.

The term `hacker' also tends to connote membership in the global community defined by the net. It also implies that the person described is seen to subscribe to some version of the hacker ethic (which states that information should be freely shared).
It is better to be described as a hacker by others than to describe oneself that way. Hackers consider themselves something of an elite (a meritocracy), though one to which new members are gladly welcome. There is thus a certain ego satisfaction to be had in having others identify you as a hacker.