how to make particle system collide with each other?

1 -I want to make particle system collide with each other, but I don’t know how.
2- I want to make water drops and collide with everything, and I think there is just one way to do it, using particle system right?

Good day.

We are not you slaves, spend some time to find the solution by your own… just by googlint it, i get 3 posible solutions… in only 25 seconds…

Bye