When a tuner maps a car, they need some way of putting the data into the ECU to state the new values.

In the old days they did it by writing a new chip, on modern ECU's they just upload the data to a rewriteable chip in the ECU.

It still gets called "chipping" in much the same way peopel still say "wing mirrors" when in fact they are on the door, or people say "choke" when in most instnaces they are an enrichment device on the fuelling not a choke on the air flow.