Matter

"Matter" means material. "Written matter" would be books, magazines etc.

"Matter" refers to a topic or subject.

I'd like to meet with you and discuss a couple of urgent matters.

"To matter" means to be important.

It doesn't matter if we have to wait till Monday to receive the order.

As a "matter of fact" is used to introduce a fact, something that is true.

As a matter of fact they didn't even return our calls or respond to messages.