Compression ratio

Hello everyone, I have a question about the compression of an engine.

For what use do people change the compression ratio of their engine?

Regards,
Wim

Higher compression to a point results in more power.

Increased compression provides more power, especially at lower RPM. Too much compression can cause the fuel to ignite too early and will cause damage.

Some people lower their compression ratio to allow their engine to run with more boost pressure from a turbo or supercharger.

Higher compression improves the thermodynamic efficiency of an engine, that is, it allows the engine to convert more of the fuel's chemical energy to force (power) instead of heat. This improves both power and fuel economy.