# What do the bracketed symbols mean in a chemical/physical equation?

i.e. ${H}_{2} O \left(s\right) \rightarrow {H}_{2} O \left(l\right)$
i.e. $\left(s\right)$ denotes the $\text{solid state}$, ${H}_{2} O \left(s\right) \equiv \text{ice}$.