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 are commonly used in various fields, including agriculture, aquaculture, and laboratory research, to ensure optimal conditions for plants, fish, and chemical reactions. There are two main types of pH testers: pH meters and pH test strips. pH meters are electronic devices that provide precise readings, while pH test strips are simple paper strips that change color based on the solution's pH level. Both methods help users monitor and adjust pH levels effectively.