... means how much a ball deforms at the moment of impact.
A value between 0 and 200 is specified here. Typically, most golf balls are between 70 and 110.
The compression is determined as follows:
The ball is loaded with a standard weight. If the ball does not deform, it is classified with a compression of 200.
If the deformation is 2/10 of an inch or more, it is rated as 0 compression.
With every 1/1000 inch deformation, the defined compression of the ball increases or decreases.
Compression is no longer the decisive factor in golf balls, but it still plays a small role in the ideal ball selection.

The "harder" a ball, the more swing speed is required to accelerate it optimally.
The modern 3 or 4 piece balls are usually suitable for higher swing speeds due to their higher compression and can "steal" a few meters for golfers with lower swing speeds.

IKARUS golf balls differ in their compression in order to offer optimal performance to different players ... from tee to green!