Flat glass, sheet glass or plate glass is a type of glass, initially produced in plane form, commonly used for windows, glass doors, transparent walls, and windscreens. For modern architectural and automotive applications, the flat glass is sometimes bent after production of the plane sheet. Flat glass stands in contrast to container glass (used for bottles, jars, cups) and glass fibre (used for thermal insulation, in fiberglass composites, and optical communication).
Flat glass has a higher magnesium oxide and sodium oxide content than container glass, and a lower silica, calcium oxide, and aluminium oxide content. (From the lower soluble oxide content comes the better chemical durability of container glass against water, which is required especially for storage of beverages and food).
Scratches can occur on sheet glass from accidental causes. In glass trade terminology these include "block reek" produced in polishing, "runner-cut" caused by grinding, or a "sleek" or hairline scratch, as well as "crush" or "rub" on the surface.