Particles in a solid are usually packed close together, with a regular arrangement. While they do vibrate slightly, they do not move from place to place.
A solid's volume and shape are fixed, which means the particles are rigid and stay in place. It is not easy to compress a solid, as there is not much space between the particles. As solid particles are unable to move past each other, it is not easy to make a solid flow.
Although gases, liquids and solids feature atoms, molecules and sometimes ions as their key components, they have significant microscopic differences. Solid particles vary considerably from liquids. For example, liquid particles have fluidity, which means it is possible to make a liquid flow. In addition, this allows them to adapt to the shape of a container, whereas solids cannot. One similarity between solid and liquid particles is that it is not possible to compress either of them. It is because of this that solids and liquids are sometimes called condensed phases.
In contrast to solids, gases also fill the shapes of their containers. In addition, there is enough free space between gas particles to compress them. Particles move around each other, which means gases flow readily.