Introduction to Solubility
Compounds differ in their solubilty in water. Chemists find it useful to classify compounds as soluble or insoluble in water.
Of course, even insoluble compounds dissolve to a small extend so insoluble really means that not much dissolves.
Soluble usually means that more that 0.1 moles dissolves in a liter of water.
Insoluble means that less than 0.1 moles dissolves in water.