Help! What is a fogger?

[greenpassion]

And where can I get one? Last winter I used a huge stainless steel pot on the stove top filled with water. I kept it steaming consistantly, which was great in the double room where my orchids live-but I want something more practical. I have been searching and searching on line, trying to learn about the best quiet most high output ones to get, but...now I see that there is a thing called a fogger. Can I use this in my house? I don't want a whole house unit, just a high output of steam to cover about 400 square feet. ??