What is WOW? I am finally curious about it. Is it too late to join? Is it complicated?

It's a MMORPG - Massively Multiplayer Online Role Playing Game.

It's subscription based, plus some content that can be bought as addons, but there is a starter version with level limits - and you can play the starter for free and then upgrade if you want to go higher.

For a lightweight introduction to MMORPG, you could try Runescape, which also has free and subscription versions, and unlike WoW, no big download, it runs in Java in the browser, and loads from there.

League of Legends is another one that can be played for free.

One drawback to most is the amount of grind required to build up ingame currency/resources for decent kit.

Buying game stuff for real money is a shortcut, but against the rules in some, silly expensive in others, and in some "free" games, the only way to actually get ahead, is to buy special items or paid for currency from the game operator - this style of game is sometimes called "allegedly free game", as free players are doomed to be weak.

World of Warcraft is a massive online game filled with players located around the globe. Each player in the game creates a character with different aspects that play an important role in the game. You quest, explore and go through dungeons with monsters with the help of friends and other players. You collect gold, buy and sell and doing professions such as Jewelcrafting and Blacksmithing. It's never to late to join, you can either join when an expansion just comes out, in the middle, or when the a new expansion is coming. Either way it doesn't matter your only going to see more features from the expansion at the start like people taking on new class's and races of the game. World of Warcraft can be complicated but coming from someone who's been playing 3 years, it gets easier every time you play and also more addicting. Any World of Warcraft player can tell you that.