Apologies Janne, that was flippant of me. A tube is used to encourage embers into flame in much the same way a bellows is used; you just blow down it to add air to the ember. They are very effective and save you having to put your face close to the fire to blow on it. A telescopic version such as a car arial or a selfie stick just makes it easier to pack.
I can't disagree to any of that but just one note; certain small amounts of technology make life a lot easier.Too much kit is sold as "Bushcraft" when Bushcraft is a set of skills - not a pack load of gear
Btw, Bushcraft = wilderness skills ? Same stuff?