Glass recycling is the process of turning waste glass into usable products. Depending on the end use, this commonly includes separating it into different colors. Glass normally comes in a number of colours. The major types are:

* Flint glass (clear glass)
* Green glass
* Brown/amber glass

Glass makes up a large component of household and industrial waste due to its weight and density. The glass component in municipal waste is usually made up of bottles, broken glassware, light bulbs and other items. Glass recycling uses less energy than manufacturing glass from sand, lime and soda. Every tonne of glass used for producing new glass items saves 315kg of carbon dioxide. Glass that is crushed and ready to be remelted is called Cullet. The term "cullet" derives from the practice of remelting flawed containers which have been "culled" from production lines.

Reuse of glass containers is preferable to recycling according to the waste hierarchy. Refillable bottles are used extensively in many European countries and, until relatively recently, in the United States. In Denmark 98% of bottles are refillable and 98% of those are returned by consumers. These systems are typically supported by container deposit laws and other regulations. In some developing nations like India and Brazil, the cost of new bottles often forces manufacturers to collect and refill old glass bottles for selling carbonated and other drinks.

Bottle Banks commonly stand beside collection points for other recyclable waste like paper, metals and plastics. Local, municipal waste collectors usually have one central point for all types of waste in which large glass containers are located. There are now over 50,000 bottle banks in the United Kingdom.Most collection points have separate bins for clear, green and amber/brown glass. Glass reprocessors require separation by colour as the different colours of glass are usually chemically incompatible. Heat-resistant glass like Pyrex or borosilicate glass should not be disposed of in the glass container as even a single piece of such material will alter the viscosity of the fluid in the furnace at remelt.

Glass is an ideal material for recycling and where it is used for new glass container manufacture it is virtually infinitely recyclable. The use of recycled glass in new containers helps save energy. It helps in brick and ceramic manufacture, and it conserves raw materials, reduces energy consumption, and reduces the volume of waste sent to landfill.

Secondary markets for glass recycling may include:

* Glass in ceramic sanitary ware production
* Glass as a flux agent in brick manufacture
* Glass in sports turf and related applications (e.g. top dressing, root zone) material or golf bunker sand
* Glass as water filtration media
* Glass as an abrasive

Mixed glass waste streams can also be recycled and converted into an aggregate. Mixed waste streams may be collected from materials recovery facilities or mechanical biological treatment systems. Some facilities can sort out mixed waste streams into different colours using electro-optical sorting units.