Breadcrumb describes the propulsion system that enables spacecraft to effectively travel faster than light.
The Breadcrumb Drive requires a Decoder Craft that detects special particles (breadcrumbs), decodes them according to a pre-programmed pattern, and enables the craft to teleport between sufficiently dense pockets of the quantum-entangled particles.
Breadcrumbs are quantum-entangled, high-energy particles that contain small bits of information, sufficient to distinguish one "type" from another. Placed along strategic trade routes and other paths, they are subject to gravity and molecular densities, and so they drift.
Seed Craft code and place breadcrumbs. These are usually unmanned, since the craft typically travels at very low acceleration on a one-way trip.
Maintenance Craft replenish the paths, ensuring the paths have sufficient density, and do not drift too far from the designated route. Sometimes, seed craft serve as maintenance craft on the way out, and create return paths.