In packaging, a bag-in-box or BiB is a type of container for the storage and transportation of liquids. It consists of a strong bladder (or plastic bag), usually made of several layers of metallised film or other plastics, seated inside a corrugated fiberboard box.

The bag is supplied to the 'filler' as an empty pre made bag. The 'filler' then generally removes the tap, fills the bag and replaces the tap. The bags are available as singles for semi-automatic machines or as web bags, where the bags have perforations between each one.

These are used on automated filling systems where the bag is separated on line either before the bag is automatically filled or after. Depending on the end use there are a number of options that can be used on the bag instead of the tap. The bags can be filled from chilled product temperatures up to 85 degrees Celsius.

There is also now a technology available called FSF (form seal fill) and pioneered by Scholle where equipment is supplied to the filler who manufactures the bags on-line from reels of film, then the FlexTap is inserted then filled on an integral rotary head filler on the Scholle line. This technology is currently limited to the packing of wine products.