The term electrolytes usually refers to a class of ionic minerals that are essential to nutrition. These include sodium, potassium, magnesium, chloride, and calcium. What defines electrolytes is that they have either a positive or negative electrical charge.
When electrolytes are dissolved in a polar solvent, such as water, they produce an electrically conducting solution. In this solution, the electrolyte separates into anions and cations, making the solution neutrally charged. Some electrolytes will break apart completely in a solution, and the solution will conduct electricity very well. Some electrolytes are relatively weak, though, and will only somewhat break apart, creating a less electrically charged solution.
In nutrition, electrolytes are important in helping the body maintain proper fluid levels. Electrolytes come from the food that you consume and are lost through sweat, feces, and urine. Your kidneys and several hormones help to maintain electrolyte levels.
Electrolytes allow fluids to travel into and out of cells. Sodium and potassium, in particular, need to be present to allow cells to maintain healthy levels of fluids. However, too much or too little of these electrolytes can lead to problems. For instance, if you have too much sodium, you will end up retaining too much fluid. As such, electrolytes are essential to fostering proper nerve and muscle function, PH levels, blood pressure, and overall cellular health.