An avalanche airbag is a backpack that contains CO2 or compressed-air cartridges that inflate a large airbag (some models use 2 airbags) when deployed by the user. Fixed to one of the shoulder straps there is a handle attached to a ripcord with which the airbag is deployed.
There are various forms for a deployed airbag, some focussing deployment around head and neck others on both sides of your pack. In whatever shape or form, the goal is to add float, literally to your body and with that to keep you more or less on top of the snow,
Avalanche airbag backpacks are manufactured by different brands, such as ABS, Snowpulse/Mammut en BCA. The airbag backpacks are sold as complete packs, but the different modules, the pack, cartridges, and trigger can also be sold separately.
The packs are reusable, by refilling or replacing spent cartridges. Having one of these packs, however, does not mean you can do without the rest of your avalanche equipment. All avalanche backpacks will provide space to pack these essential items.