The process whose specific outcome is the progression of the lateral line system over time, from its formation to the mature structure. The lateral line system is a network of sensory organs (neuromasts) and lateral line nerves located superficially on the skin or just under the skin in fluid-filled canals on the head and body of all fishes and most amphibians. The lateral line system develops from cranial ectodermal placodes situated between the eye and ear.