pH is an abbreviation for 'potential of hydrogen'. It's a way of measuring acidity levels in any given environment, product or our skin! Our skin types all have different acidity levels and, therefore, a different pH value. pH values are measured on a scale of 0 (most acidic) to 14 (most alkaline). When we talk about pH neutral, it means a value of 7. However, when it comes to skin, values vary between 5.2 and 7. In other words, our skin's pH level determines whether we have dry, normal, oily or combination skin. It's also the reason why we need to carefully choose products according to our skin type.