What is a conservatory?

I have a Facebook friend in Canada who I was speaking to this afternoon. He asked what I was doing and I mentioned I was sat in the conservatory.

"What's a conservatory?" He asked.

Well rather than explain I sent him a picture... Can't believe he's never heard of one! Lol

For those who aren't at home relaxing in the conservatory, sat behind desks or in meetings etc :( I'm thinking of u. :)