What is outside of solar system?

Mostly nothing, empty space. A long long way in the distance you find other stars, here and there, many of which have systems of planets revolving around them. But mostly space is really really empty.

Planets, stars, galaxies, a huge void of space with only a very few molecules per cubic meter. We have actually sent two spacecraft that have traveled outside of the solar system (just within the past year or two have they gone beyond the area of the Sun's solar wind) -- You might want to search for NASA Voyager spacecraft

Empty space...lots of empty space. Travel a few hundred billion miles and you'll reach the next star, Proximus Centrui. Then the Milky Way, the the 200 billion other solar systems that make up our universe.

Lots of other solar systems that make up this galaxy. And, beyond that, can be found an enormous number of other galaxies.

There are more solar systems,planets & moons, stars, galaxies,gas debris comets/asteroids and empty space

our solar system's boundary which is in extreme position from sun. after this, there is generally gravitational field of very frequency of gravitational waves produced from nearest stars from sun. i.e after Oort cloud, there is interstellar medium. it is possible to escape some less massive object from Oort cloud due to wave frequency produced by nearest stars. After many years, pioneer spacecrafts will give us information about that.

Interstellar space, then eventually other solar systems, or nebulae, etc.

It's basically nebula's,black holes,stars, super giants,dwarfs,planets, Galaxy's around us,dark matter and some other objects in the outer world.

Mankind is still too young to know just yet. But soon all of us will be ready to know.

Everything else.