World of Warcraft: Lich King's icy changes include Achievements
Wrath of the Lich King is all about the return of Arthas Menethil, a paladin trained by Uther Lightbringer, and later on corrupted by the cursed blade Frostmourne, hence becoming a death knight.
This expansion brought upon a new continent to explore, a new profession, a new skill level (Grand Master), a raised level cap and new dungeons and raids, as you would've expected.
Let's start with the new profession, Inscription. With this, you can create many glyphs for every class, some are just for fun, some are really useful. What these glyphs do is that they change certain mechanics of your spells, they can make some spells to do more damage, they can have an added effect, etc. The complementary profession this one needs is Herbalism, you get the ink you need from herbs.
World of Warcraft: Wrath of the Lich King Cinematic Trailer
The level cap was raised to 80 this time, and we have a whole new continent to explore and have fun in, Northrend. This continent IS a part of Azeroth, unlike Outland in the previous expansion. So we have new quests, zones and monsters to interact with, and of course, a new set of dungeons and raids. Now, the only difference in the PvE mechanics this time was that they also added various modes to raids, you can either do them on 10 or 25 man, and you can also unlock a heroic mode in there as well.
There weren't many changes PvP-wise, except for a few new battlegrounds. But a big addition they made was the Achievement System. WIth this, players get rewards after completing certain achievements, which go from titles to mounts, to even vanity pets. This was a nice addition since now you can actually keep track of the deeds you've done so far, and it's a nice way to spend some time when you don't feel like raiding or killing other players.