The dominant commercial glass family made mainly from silica with sodium- and calcium-containing ingredients that make the glass practical to melt and chemically stable enough for common use.
GlassRenu · Educational illustration
Meaning and boundaries
Not identical to every type of glass. Borosilicate, aluminosilicate, lead, fused-silica, and glass-ceramic products behave differently.
Why it matters in glass restoration
Most architectural restoration guidance should identify this composition as the assumed substrate unless another glass family is known.