YOU ARE LEARNING:
Loci are points that are the same distance from two objects. We can construct loci in a way that is geometrically accurate using a compass and a ruler.
A locus is a point that moves in line with a rule.
Loci is just the plural.
A car driving around a track is following a path, this path is a locus.
A locus can also be an area, defined by a rule or sometimes multiple rules.