Entropy

H2O as a solid (ice)

1 BCE

Water as solid ice have low entropy because they don't move easily so they have fewer possible states

H2O as a liquid (water)

1 BCE

Water as liquid water has more entropy than solid water because the molecules are sliding by one another, so the molecules have more options or more possible states.

H2O as a gas (steam)

1 BCE

Water as a gas has the most entropy of the three states here because the molecules are moving around very quickly. These molecules are in constant random motion meaning that at every instant, the molecules are in a new possible state; this means there is a lot of entropy. The photo here is the steam produced by the heat in a nuclear power plant.

An example of options (few states) and low entropy

1 BCE

This phone screen has 16 icons on it. It can be arranged 16! ways. Thats 20922789888000 different options.

An example of moire options (many states) and high entropy

1 BCE

This phone screen has 140 different icons in 9 folders. Thats 140! or 1.34620125 x 10^241 different possible arrangements