Rumen pH is often viewed primarily as an indicator for detecting rumen fermentation disorders such as subacute ruminal acidosis. However, this view is too limited: rumen pH influences, among other things, the composition of the rumen microbiome, the ratio of volatile fatty acids, fiber digestion, and the production of hydrogen as a substrate for methanogenic archaea. Continuous pH monitoring makes fermentation patterns visible and enables the targeted management of the optimal balance between methane reduction, feed efficiency, performance, and animal health.