It can serve multiple purposes. You can have 0 ohm resistors to serve as a bridge to run a trace below if you're running out of space. You can have multiple re

It can serve multiple purposes. You can have 0 ohm resistors to serve as a bridge to run a trace below if you're running out of space. You can have multiple resistor footprints and depending on where the 0 ohm is placed, different configurations are enabled. You can use it to be able to isolate parts of the circuit after the fact, although solder jumpers are more common for that purpose