What is knowledge?

Sorry for the radio silence on my part lately. My house got broken into... again... and I'm dealing with the fallout. I'm thinking about a post on knowledge, where it comes from, what it's good for and if it matters. But before I write it, I'd like to get your input.

What do you think "knowledge" is? Is it different than Truth?

Do you agree with the idea, "Ignorance is Bliss"? Is it ever? What about, "Where ignorance is bliss, 'tis folly to be wise?"

What does it mean to be wrong?