World of Warcraft will run on both Mac and Windows PCs, and before you buy the game you should definitely make sure your computer meets the minimum system requirements. They're fairly modest, so there's a good chance you're fine unless you're using an older computer.
All systems will need at least 25 GB of available hard drive space, a broadband internet connection (since the game is played online), a keyboard and mouse, and a 1024 x 768 minimum display resolution. For Macs, the minimum requirements are OS X 10.7 on an Intel Core 2 Duo processor with 2GB RAM and an NVIDA GeForce 8600M GT or ATI Radeon HD 2600. And for Windows, the minimum requirements are Windows XP or Vista on an Intel Pentium D or AMD Athalon 64 X2 with 2 GB RAM and an NVIDIA GeForce 6800 or ATI Radeon X16000 Pro. If you're just scraping by with minimum stats, you'll probably be running the game with lower quality visuals, but if you have anything better than those stats, the game will run better.
If that's all gibberish to you, don't worry: If you've bought your computer in the past 5 years, it probably meets these requirements. Also, before you commit to buying anything you can test out how the game runs by downloading the Starter Edition.
Get started with the Starter Edition
If you want to dip your toes into World of Warcraft but aren't sure about whether you're willing to commit, you can play (to an extent) completely for free with the Starter Edition. These free accounts have a number of limitations -- many of them involving communication -- but it's a good way to try the game out and see if you like it. If you level your starter character to 20 and want to keep going, you can upgrade your Starter Edition to the full game either online or by buying a boxed copy, whichever you prefer.
If you have friends playing WoW, ask them if they'd Recruit a Friend for you -- you'll both get benefits by doing so, like faster leveling. But even if you don't know anyone, it's easy to get started by heading to the Starter Edition sign-up page -- you'll need to provide some basic information, but you don't need a credit card or any other form of payment. After you've signed up, you'll have to download the game client, which will take a while, so don't plan on jumping in right away. However, you can get into the game as soon as essential files have been downloaded, so you'll be able to start playing sooner than you'd expect.
So you've tried the game out and you like it enough that you want to buy it. To start playing, you'll want to buy the WoW Battle Chest, either digitally through Blizzard's store or by picking up a boxed copy at your retailer of choice. Since there's no real gameplay difference between the two, we prefer the convenience and speed of buying digital copies.
The Battle Chest comes with the base World of Warcraft game (which players will often refer to as "vanilla"), the first two expansion packs (The Burning Crusade and Wrath of the Lich King), and 30 days of game time, all for about $20. This is more than enough to get started, as you'll be able to play up to level 80 and even play new races like the worgen and goblins introduced in Cataclysm and the pandarens introduced in Mists of Pandaria all without buying and installing the newer expansion packs.
However, if you want to level past 80 you'll have to pick up the Cataclysm expansion ($10) and if you want to level past 85, you'll have to pick up the Mists of Pandaria expansion (which is new enough that it still retails for around $40). If you want to play Mists of Pandaria's monk class, no matter the level, you'll have to have both Cataclysm and Mists installed -- so if you aren't sure about spending the money, we recommend seriously considering the game's other classes.
If you're serious about playing the game beyond the Starter Edition -- to whatever level -- we strongly recommend using the free authenticator app to secure your account. It may seem crazy, but there are hackers who are interested in stealing your WoW account and having an authenticator can stop them cold -- and let you keep enjoying your game time.
Paying monthly subscription fees
Even though you've paid up front for the game box, WoW requires a monthly subscription fee for you to keep playing. After the first month -- which comes included with your game purchase -- you'll have to pay for additional game time. The fee varies depending on how much you pay for: if you pay month by month, it will cost $15 a month, but costs drop to $14 a month if you pay for 3 months at a time and $13 a month if you pay for 6 months at a time.
You can use a credit card or PayPal account to set up a reoccurring subscription payment or you can pay by buying game time cards, which provide 60 days of gaming for $30 (or $15 a month). It's easy to cancel or change your subscription at any time by logging on to your Battle.net account.
So now that you have your own copy of World of Warcraft, what do you do next? You'll probably want to create your first character on whatever realm your friends play -- or read up on what different types of realms -- and maybe take a look at our newbie class guides for some info on what the different classes can do. Once you've picked a class, though, dive in and have fun!
Just because you're a newbie doesn't mean you can't bring your A-game to World of Warcraft! Visit the WoW Rookie Guide for links to everything you need to get started as a new player, from the seven things every newbie ought to know to how to get started as a healer or as a tank.