It has to take up space. (Have mass)
If there is a 'something' there, then trust me, there is matter in it.
No, because matter is something that takes up spaces, and matter is something that you cant see.
There is not anything in the world that is not made of matter, because something that is not made of matter is not anything at all.
You say that something is a matter when there is mass and occupies space.
matter
An idea is not matter (and sometimes does not matter either).
Yes, matter can be something that you can not see. This is because one form of matter is gas, which can not be seen.
Everything that consumes something of matter expels something of matter. So yes, they do.
Anti-matter
If something has mass it is matter.
If it has mass and volume, it is matter.
I know this book is made of matter because it is something around me. Now you think of something that is made of matter.