Sea glass is glass that has been thrown in the ocean and weathered by the salt water. Over many years, the glass loses its shine, becomes frosted with smooth edges and washes up on the beach.
Sea glass used to be easy to find, but as more and more bottles are being made of plastic, sea glass is getting harder to find. Sea glass is found on beaches, just like shells. The more frost a piece of glass has, the better its quality.
Sea glass should not be confused with beach glass. Beach glass is the same as sea glass, only it is found in fresh water, such as lakes and rivers.