An asteroid group or minor-planet group is a population of minor planet

Minor planet

An asteroid group or minor-planet group is a population of minor planets that have a share broadly similar orbits. Members are generally unrelated to each other, unlike in an asteroid family, which often results from the break-up of a single asteroid...

s that have a share broadly similar orbits. Members are generally unrelated to each other, unlike in an asteroid family

Asteroid family

An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions...

, which often results from the break-up of a single asteroid. It is customary to name a group of asteroids after the first member of that group to be discovered, which is often the largest.
There are relatively few asteroids that orbit close to the Sun.