A H-bomb is a BYOH (Bring Your Own Hydrogen) device - the weapon includes a helping of deuterium (hydrogen with an extra neutron). The fusion reaction requires

A H-bomb is a BYOH (Bring Your Own Hydrogen) device - the weapon includes a helping of deuterium (hydrogen with an extra neutron). The fusion reaction requires an awful lot of energy to get going, so it basically uses a fission bomb as a detonator.