What's osmotic pressure and how does it relate to passive transport?

Question

I've seen many definitions but they all confuse me....
can someone put it simply?

Answer 1

Osmotic pressure is the difference in the water concentration on different sides of the membrane. Osmotic pressure can cause solutions to pass through the membrane from higher pressure to lower pressure. It's passive transport because the cell does not have to spend any energy in order to make it happen.