If I want to begin to play World of Warcraft, do I need to buy every update released from the beginning?
There are only two purchasable items:
- A subscription, giving access to everything up to and including the Legion expansion;
- The newest expansion, Battle for Azeroth, which is sold seperately.
But use the Starter Edition first! You can download the game without purchasing anything. The starter edition stops your progress at level 20, but you can play as much as you want. If you enjoy the starter edition then subscribe to continue leveling.
These expansions are now part of the base game and not available for separate purchase: Burning Crusade, Wrath of the Lich King, Cataclysm, Mists of Pandaria, Warlords of Draenor, Legion.
You only need the core game to start playing. This gives you access to the 8 original races (No Draenei, Blood Elves, Worgen, or Goblins), and 9 original classes (No Death Knights), and a level cap of 60.
To reach level 70, you will need The Burning Crusade, level 80 requires Wrath of the Lich King, and Cataclysm unlocks level 85. Each subsequent expansion requires that you have the prior ones. It is not possible to install Cataclysm without Wrath, or Wrath without Burning Crusade.
After realease of BFA datadisk you need ONLY the newest datadisk and subscription. For example when you create new account, you will play first 20 level for free. When you want to continue to level 110 you need ONLY to have subscription. If you want to have content from BFA in your game and continue to level 120 you need buy this expansion.
If you're aiming for raids and top level content, I advise you to buy all the expansions from the beginning.
If you want to explore the world with your friends, you could play 2-6 months just in the basic game (World of Warcraft). There are interesting places and plenty of content, even for low level characters. I think there was a sale a while ago: World of Warcraft, The Burning Crusade and Wrath of the Lich King for 20 Euros, you could try to wait for another one.
I HIGHLY recommend getting the trial before committing to all the games. It's true that you won't be able to play a Worgen, Goblin, Blood Elf, or Draenai right off the bat, but it's better than shelling out the cash for all the games and realizing 2 days in that the game really isn't for you.
Even though WoW is extremely popular, it's an acquired taste. If you've never played it or don't know very much about it, you're better off getting the trial.
If you enjoy the trial, I recommend going to the store (or on Amazon) and purchasing the hard copy of World of Warcraft & World of Warcraft Burning Crusade. It comes in a bundle pack with both the games and I think it costs somewhere around $20. If you buy each separately, then it'll cost more. I don't think there are bundles with Wrath of the Lich King and Cataclysm.
It's also important to note that you can't play an expansion without the previous expansion. Here are the releases in order: World of Warcraft World of Warcraft: Burning Crusade World of Warcraft: Wrath of the Lich King World of Warcraft: Cataclysm
As of Oct 2014, all expansions except for the latest one (Warlords of Draenor) are free with the purchase of the base-game.
You only need Warlords of Draenor to reach the very end-game content, after level-90. However, note that the purchase of Warlords of Draenor includes a powerup to boost a single character to level 90 instantly.