Basic networking facilities have part of the Mac OS since beforeSystem 7. Networking can be accomplished in a variety of ways,using something as simple as a serial cable (for older Macs thatsupport AppleTalk) or a crossover ethernet cable.
Its most obvious use is for sharing files. If your Macs arenetworked (using any of several methods that we'll get into in abit), you can transfer files from computer to computer withoutusing CDs, Zip disks, USB drives, or even floppies (rememberthose?).
There are a variety of ways to connect one or more Macs toanother. The simplest, least costly way is using ethernet. All youneed is twos Mac with ethernet ports and one cables. Macs haveincluded ethernet ports since the Quadra era, when you needed touse a cable adapter, and most Macs built since the beige G3s came with 10Base-T ethernetports built in.
In its simplest form, you can use a crossover ethernet cable toconnect two computers together.
Once you get past two computers, it gets a bit more complicated.For more than two computers, you need a hub. A hub allows severalcomputers to connect to each other using cables running from thehub to each computer. Hubs are combined with a router these days,which lets you share your Internet connection with all yournetworked computer - we'll explain that in a bit.
There are other ways to set up a basic computer network withoutusing ethernet. Older Macs can use a serial cable to connect to oneanother. While not very useful now (Macs haven't included Apple'sold serial port since about 1998), it can be used to get files offan older Mac, but not much else.
For newer Macs that have AirPort, there is a much better option.Using a collection of computers with AirPort or Airport Extremecards, you can create a wireless network. This doesn't require useof a hub (or base station, in AirPort lingo), you can createtemporary networks. This is useful to connect, say, two iBooks atan office to exchange data. You can create permanent networksbetween wireless computers as well.
iTunes File Sharing
As I discussed a few weeks ago, iTunes file sharing is a great way toshare your music on a network. While it does have some limitations- such as only allowing five users at a time to connect - it makesmanaging one library for all of your computers very easy.
To turn on iTunes music sharing, all you need to do is go toiTunes preferences and select sharing. Click "share my music," andyou're all set.
Internet Sharing with a Router
Internet sharing is a big use of networking today, especiallywith many people making the switch from dialup Internet tobroadband access. While you can share a dialup connection, it'sfar slower (thus less practical and useful) than broadband sharing.Splitting a slow-speed connection with a lot of computers can bequite irritating.
With this Internet sharing, everyone on your network can get onthe Net while paying for a single Internet connection.
Using a router connecting a broadband modem to the rest of yournetwork, you can share your connection with the entire network.Setting up Internet sharing in this fashion is good because it'sgenerally easy and trouble free.
Additionally, many routers have wireless capabilities. Havingwireless capabilities on your router allows you to have both wiredand wireless computers on the network. Most home networks are setup using a configuration of both connection types. A good 802.11gwireless router can be had from anywhere from US$20-50. Some canreach speeds of up to 108 Mbps. With all the cards and cablesyou'll need, you can have a modern network for under a few hundreddollars.
Wireless Internet Sharing Using Software
OS X has built-in software to facilitate Internet sharing. Touse it, you need an Internet connection connection and hardware toshare that connection. You can use it to share a dialupconnection, but that's slow and not very practical.
Internet sharing is usually done using the Mac's ethernet portto connect to the Internet and an AirPort card or AirPort Extremecard to share that connection. Sharing this way is extremely usefulfor people who want to add wireless capabilities to an existingnetwork without adding a wireless router.
For instance, Temple University (as well as many othercolleges), don't allow you to have a router connected to itsnetwork. To work around the fact that I have an eMac and an iBook,I could use the AirPort Extreme card to broadcast the Internetconnection from the wired eMac to the iBook's AirPortcard.
To enable Internet sharing, you must open up the "sharing" panein System Preferences. Click the "Internet" tab. Then select"built-in Ethernet" from the dropdown list and click the check boxnext to AirPort. Click the start button, and you're all set toshare your connection wirelessly.
You can even share your wireless connection with a WindowsPC.
Printer Sharing
Sharing a printer using OS X is one of the most useful featuresof the sharing pane in System Preferences. Printer sharing can saveboth time and money, since you'll be able to use one printer as ifit were hooked up to each computer. A network with a shared printerallows you to skip the cost of buying multiple printers and thetrouble of transferring documents from one computer to another soyou can print it.
Setting up OS X's built-in printer sharing is easy. All you needto do is connect your USB printer to the computer that you'll beusing it with, go into the Services tab of the Sharing Preferencepane, select Printer Sharing, and then click start.
From here you're all set to enjoy the niceties networking yourMacs can offer. 
