wardriving is the idea of hacking wireless networks, also referred to as wifi (wireless fidelity), or 802.11 ethernet. there isn't really a whole lot to say about it. many companies and cyber cafes take advantage of this technology so that you can walk around with a laptop and no need for plugs.
basically, you get in your car with a laptop and wireless network card, maybe some software to help pick up signals, then you just drive around seeing what you can find. many wireless networks aren't encrypted, so you can just hop right in, and for other networks that are encrypted, you can find software that attempts to crack the encryption. cracking an encryption can take hours or even months depending on how active it is. so what's the point? i don't really know; other than being a snoop or trying to mooch free internet there really is no point to wardriving.
considering the future will probably have wireless technology everywhere, you won't even have to drive to wardrive anymore. what will they call it then, warsitting?
warchalking is the idea of leaving graffiti behind after you've found an exposed wireless network. this graffiti allows other wardrivers to see information about the network without using a computer. the following symbols are quite popular:
)( = an open node, or "bellum"
o = a closed node, or "pax"
bellum and pax are latin for war & peace
= wep (wired equivalent privacy), an encrypted node.
encrypting your internet traffic on a wireless network or even a non-wireless network is always a good idea. unless you'd prefer painting the walls of your house with an aluminum based substance, to prevent your wireless signal from leaving.
not a good idea to keep your money in a bank with any of the above symbols chalked outside.