Download means to copy a file from another computer to your computer. With hotComm file sharing, when you copy a file from another peer, you are downloading the file. (Also see Upload.)
A firewall is any combination of hardware and software that creates a barrier between your computer and the Internet. Firewalls are designed to prevent outsiders from accessing your computer, and to prevent viruses and other destructive software from getting in. Corporations have used firewalls for many years. With the widespread use of DSL and cable modems, homes and small offices are using firewalls.
IP (Internet Protocol)
IP is an Internet address consisting of a string of numbers, such as 126.96.36.199. Your computer has an IP address. It may be static (unchanging) or dynamic (changes from time to time).
NAT (Network Address Translation)
Network Address Translation is a system that allows each individual computer in your corporate or home network to have an individual IP address inside the network, while sharing a single external IP address. If you are using a cable modem or DSL router and a network, you probably using NAT.
For an excellent description of NAT, see How Network Address Translation Works at Marshall Brain's HowStuffWorks.
A proxy server is a computer that is in between your computer and the Internet. Your computer sends requests to the proxy server, which sends them on to the Internet. Replies come back to the proxy server, which relays them on to you. The proxy server can examine the requests and block any that it determines to be inappropriate.
A router joins networks and determines where each message or file is supposed to go. The Internet is a huge network and contains many routers. If you have a network in your office, you may have a router that determines which traffic stays inside your network and which goes to the Internet. It also receives incoming Internet traffic and sends it on to the appropriate computer.
Upload means to copy a file to another computer. With hotComm file sharing, when someone copies a file from your computer, the file is being uploaded from your computer to their computer. (Also see Download.)
URL (Universal Resource Locator)
URL is an Internet address consisting of text characters, such as www.hotcomm.com. URLs make it easy to remember web site names, but behind-the-scenes, the URLs are converted to IP addresses for processing.