In case you weren't sure, "World of Warcraft" is a massively multiplayer online role-playing game, or MMORPG for short. That means it takes place in a huge, persistent world where players run around and do quests with each other, level up, collect loot and maybe even fight each other.
Before "World of Warcraft" came along, the most popular MMORPGs were games like "EverQuest," which were not especially welcoming to new players, comparatively. It was a different time, so expectations were different.
"World of Warcraft" did a better job of explaining the more arcane aspects of the genre and easing newcomers in, even if it wasn't perfect. It's actually a much more friendly game now than it was at launch, too. This is a great time to jump in.