An explosive booster acts as a bridge between a low energy explosive and a low sensitivity (but typically high energy) explosive. It increases the energy of an initiating explosive to the degree sufficient to trigger the secondary charge.

For example: An initiator (such as detonation cord, shock tube, or cannon fuse) does not have the energy to trigger large high explosive charges (such as PETN, TNT, or ANFO), so a booster is used to upgrade the energy so that the main charge is activated.

Explosive boosters are typically constructed by mixing high sensitivity and high energy compounds at various ratios.