Bar codes

Hello! Sorry if this is off topic. I'm making a php site where one can order a kit and now I would like to mark the kits with bar codes generated by the php script. I would also need some kind of bar code hardware reader and some way for a computer to read the result from the bar code reader, guess php might not work here so I might create some java application or whatever. I've never done anything like this before, do you know of any good starting points? I don't know anything about bar codes. Regards Emil