Complex sentence: Carbonated water (also known as club soda, soda water, sparkling water, seltzer water, or fizzy water) is water into which carbon dioxide gas under pressure has been dissolved, a process that causes the water to become effervescent.
Split into simpler sentences: Carbonated water (also known as club soda, soda water, sparkling water, seltzer water, or fizzy water) is water into which carbon dioxide gas under pressure has been dissolved. This process, known as carbonation, is a process that causes the water to become effervescent.