Electrolyte tabs are also known as hydration tabs, because that’s what they are—tablets containing electrolytes that your body needs to be properly hydrated. The most important electrolyte they provide is sodium. These electrolytes are also found in sports drinks, often alongside carbs and sugars which help fuel your exercise. Tabs just have the electrolytes, no carbs or cals, so they’re purely for hydration. Drop one in water, let it fizz for a couple of minutes, then glug it down.