Interstellar space is the space that exists between stars in our galaxy, the Milky Way. It's like the space between your fingers when you hold your hands apart.
In this space, there is no air for us to breathe or food for us to eat. It's very dark and cold because there are no stars nearby to give off heat or light.
This is the space that spacecraft like Voyager 1 and Voyager 2 are exploring. They left Earth a long time ago and are now traveling through this interstellar space. To do this, they need special equipment like solar panels to power their machines and radio antennas to communicate with us on Earth.
Scientists study interstellar space to learn about the stars and planets that are far away from us. They study the radiation that travels through this space to understand how it affects our solar system.
Overall, interstellar space is a vast and mysterious space that we are still trying to understand.