Lag is a thing
Lag sucks, but it's somewhat unavoidable. When you're running along an open field in the game, and suddenly everyone else in the world stops moving? That's lag. When you walk into a busy city square and your game stutters, that's lag, too.
Lag generally refers to any time the game struggles to keep up with your action or maintain a smooth flow of communication between your computer and the server. While all these situations aren't technically lag in the sense that a computer expert would use the word, most players just lump it all into the single lag category.
What can you do about lag? That's deeper than this article can get into, but we have two rules of thumb you can get started with. First, check to make sure nothing in your house is streaming music or video. Streaming media can be a bandwidth hog, and if Netflix is fired up on another computer, that might affect your game. It really shouldn't, but you can check. Second, turn down the game's graphic settings. If your computer is struggling to render all the pretties, you can end up with choppy performance.
Other players in your world
One of the most defining characteristics of an MMORPG is that you play in a world chock-full of other people. Other players dot the landscape, chat in universal channels, and team up to do amazing things. In an MMORPG, you are not alone.
In WoW, you can generally tell a person is another player (and thus "PC," for player character) if their name sounds like a PC name instead of something like Hulking Bonenommer. While player names appear in green, yellow, and red, that scheme is actually shared with various non-player characters in the world, too.
You'll get good at figuring out which characters are PCs and which are NPCs pretty quickly. For now, just be aware that other players are out there. Feel free to say hello!
People to meet, resources to read
One of the nice things about the huge swarms of players who love and live WoW and other MMORPGs is that the game doesn't have to start and stop in Azeroth. It might sound a little funny to say this sort of thing on a community site, since you obviously aren't reading this while inside the game. But still, it helps to know that the game is full of good people who want to help out, want you to have a good experience, and would be thrilled to call you a friend.
The warm embrace of an MMO's community is probably one of its biggest draws. In the same way a few gamers get together and chat about geek stuff, WoW players love to gather and argue about lore, play style, and fun.
So if you find something in the game troublesome or difficult, jump to your friendly search engine and just google your question. You'll find plenty of answers and maybe even a few friends along the way.
How you play and the label
You tend to hear many labels for gamers and how people play the game. Don't get too caught up in it; these are more descriptors used by people to advance or defend an argument. The words don't really mean anything; they're just used to make a point. That being said, here's what they tend to mean:
PvP player Generally, this is someone who particularly enjoys the competitive, player-versus-player environments in a game.
Raider or PvE player Not terribly interested in PvP, a raider is someone who wants to tour the content and defeat the game's story. Raids are huge gatherings of PvE players who defeat large bosses impossible to fight alone.
Auction House Someone who plays the AH is just someone who prefers to dabble in the game's economy, using crafting and the Auction House to gather in-game wealth.
Casual Boy, this label gets thrown around a lot. What someone really tends to mean when they say casual is someone who doesn't play as hard as they do. It's a loose term but can also be meant to say "I just play a little bit."
But again, these labels are useless for the most part. Don't get caught up in them. The point is to just play the game and have fun.
Visit the WoW Rookie Guide for links to everything you need to get started as a new player, from how to control your character and camera angles when you're just starting out, to learning how to tank, getting up to speed for heroics and even how to win Tol Barad.