Space is considered the boundless three dimensions that objects are able to move relative to.
Space is so interesting, but so complicated! Does it really go on forever?
Yes there is no end.  There is also a boundless four dimensional continuum called spacetime.
I didn't realize! Do you study space for a living?
No, but the concept of space is fundamental to understanding the physical universe.
My son is really into space. He's always talking about black holes and how neat they are. What is a black hole?
It is known as a region of spacetime with such strong gravitational pull not particles can escape including light.