Canning is an example of preserving food by sealing. Its history is inseparable from that of bottling; so the two are treated together here. Each involves heating food to sterilize it and sealing it in an airtight container. However, the use of metal containers (cans) soon became dominant in the canning industry, while bottling in glass containers was the usual practice in domestic kitchens (although it has continued to be used in the food industry for specialized or expensive or visually attractive items (e.g. fruit in syrup)).