One of the remarkable visible signs that indicates a precipitation reaction when two solutions are mixed is the formation of an insoluble solid. The insoluble solid formed is the precipitate.
Precipitates usually forms in single replacement reactions and double replacement or double decomposition reactions.
They form when two soluble compounds react. One of the product is an insoluble solid in the solution called the precipitate.
The solubility table helps to predict whether precipitates forms in a reaction.