Many modern cars are now fitted with an ECU (Engine Control Unit), this is essentially the brains or computer of the car and is there to control how the engine works. It receives information from sensor and actuators that work to manage the engine.
When cars are manufactured, the ECU’s are all set to the same standard manufactures settings; there is nothing wrong with this because the cars are shipped all over the world and need some basic settings to be able to work well in different climates also many countries have different laws and restrictions for the road along with different types of fuel.
When One Stop Electronics remaps an engine, they are making the ECU respond in a way that is bespoke to the driver, so if you tow a caravan, want improved fuel efficiency or a bit more bhp, One Stop Electronics can produce a new software upgrade for your ECU.
To remap an engine, modifications are made to the default ECU software manufactures settings.