Severally I have heard people write and say "Is well". Just like when you chat with someone and ask him about his business or well being, he will reply "is well".

My question is, is it proper to say "is well" or is it "it is well". Personally I think the right usage is "it is well" but with the massive number of people using "is well" I am beginning to be confused.
Nairalanders please help me with the correct usage.

My brother, it is well.