pH testers are devices used to measure the acidity or alkalinity of a solution. They provide a numerical value on a scale from 0 to 14, where 7 is neutral, values below 7 indicate acidity, and values above 7 indicate alkalinity. These testers can be simple strips that change color or more advanced electronic devices that provide precise readings. Commonly used in various fields, pH testers are essential in agriculture, aquariums, and laboratories. They help ensure optimal conditions for plant growth, maintain healthy aquatic environments, and conduct scientific experiments. Accurate pH measurement is crucial for many chemical processes and biological functions.