Solipsism is the idea that you are the only 'real' person in the world. Your mind is the only one which you can be certain of and so it's possible that everyone else around you is therefore not 'human' in the sense you are.
Some people get really freaked out by this suggestion and find it hard to shake off. I've always liked it but never really found it upsetting. I also think it is true. You are the only real person in the universe, everyone else is not the same, they're unique, as are you.
It's important though to define terms.
Real - what does that mean? Person - what's one of those?
Firstly "real" is something you personally can verify. Reality only ever reaches us as a subjective impression of apparently external sources. Your version of "real" is different to mine. My version of "real" will, somewhere along the line, deviate from yours and become un-real.
This brings us to the question of what is a "person". Well, it's the identity you attribute to the instrument which allows you to see your version of 'real'. So a "real person" would be best described as someone who sees your version of real. Thus the only real person you know is the one with your name.
There's nothing upsetting about this, it's better than discovering that in fact everyone else has the same perspective as you. That would cause much bigger problems.
Accepting solipsism as a necessary quirk of perspective is a worthwhile step. Jumping on from there to the conclusion that this invalidates the rights of other people is to forget that your perspective is incomplete and that without others you live in a smaller world.