Black Matter

During high school I had attended a school field trip that visited a lecture. One guy was talking about black matter. In his trying to sound very intellegent he never broke down what he was talking about. The only thing I got out of it was that black matter makes up as much as 90% of the universal matter. We can only see the 10% which reflects or gives off light. Have you heard of this, and is so, can you tell me a little bit about it? Thanks. -Matt