A "Litmus Test" is a simple method used to determine the acidity or alkalinity of a solution. It involves using a special paper that changes color when it comes into contact with acidic or basic substances. This test is often used in chemistry to quickly assess the pH level of a liquid, helping scientists and researchers understand its properties. In a broader context, the term "Litmus Test" is also used metaphorically to describe a decisive factor or criterion for evaluating something. For example, in politics, a candidate's stance on a specific issue may serve as a litmus test for voters, indicating their overall alignment with the candidate's values.