* Solids: In solids, the molecules are tightly packed together and have very little free space between them. The strong intermolecular forces keep the molecules rigidly bound. Applying pressure simply causes the molecules to push against each other, which is very difficult to overcome.

* Liquids: Liquids are more compressible than solids because their molecules are more loosely packed, allowing for a slight reduction in the spaces between them when pressure is applied.

* Gases: Gases are the easiest to compress because their molecules are very far apart and have weak intermolecular forces. When pressure is applied, the molecules are pushed closer together, significantly decreasing the volume.

Think of it like this:

* Solid: Imagine a tightly packed box of oranges. You can't easily squeeze more oranges in.

* Liquid: Imagine a bag of marbles. You can press some of the marbles closer together, but not as much as with a gas.

* Gas: Imagine a room full of balloons. You can easily compress the air in the room by squeezing the balloons closer together.