Newb question again.

I know what Mhz are regarding transmitters and receivers, but what exactly is a channel? I just bought a transmitter on Channel 60 in the 72 Mhz band. What exactly does that mean?

Regarding the transmitter, I hope I didn't make a mistake. I saw a deal on eBay and bid on it not really thinking I was going to get it. Stupid me didn't even ask any questions. Basically it's a JR Max 4 channel transmitter on channel 60 (whatever that is) and 72 Mhz. Here's a link w/picture:

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEBWN:IT

I only paid $20 for it which is what makes me nervous. It must be a bad transmitter if no one else was wanting it. In any case, its just a temporary one until I come across the funds to buy a nice transmitter and plane.

Thanks,
Mark