As defined by Wikipedia:

ding - Jargon for advancing a level in many video games, particularly of the role-playing genre. It originates from Everquest as there was a "Ding" sound when you leveled up.

Why do you care? (Well honestly, you probably don't. )

That's right, read it and weep, n00bs! It took a while, but I finally overcame my natural gaming attention deficit disorder and played one game long enough to reach the level cap. Yay me!

Here's a screenshot of the actual Ding moment (click to bigify)...

The game is Lord of the Rings Online (blogged previously here and here), and it's far from over despite the level cap. There's lots of high-level content to see and phat loot to acquire. The beauty of LotRO is that there's a ton of Middle Earth left for the developers to add to the game in the form of free updates, and eventually a paid expansion or two. (I can't wait to explore Moria!)

That's not to say I'm not looking forward to other games, but Lord of the Rings Online will be my home (literally) for some time to come.

p.s. In LotRO the level up sound effect is actually closer to a "whoosh" than "ding".

p.p.s. In the interest of full disclosure, I was the last of my regular gaming group to level up. However, I contend that they cheated... How dare they continue playing when I'm lazy and/or not in the mood!