Sea glass is glass that has been weathered by saltwater and is found on beaches. It is ultimately derived from glass waste (bottles, windows, jars, etc.) that ended up entering the ocean. It is physically weathered in the water by wave action to produce smooth edges and interesting shapes. It is also chemically weathered by the saltwater to produce a frosted look due to acidic etching. Carbon dioxide from the air dissolves in the ocean water to form small amounts of carbonic acid (H2CO3). This is a weak acid but over time it can acid etch glass to form sea glass. But please be aware that sea glass is not actually created by the sea. It is pre-existing glass that is weathered by the sea.
Sea glass is glass, found on beaches, and has been weathered by saltwater.