Test strips are small, thin pieces of paper or plastic that are used to measure specific substances in liquids, such as blood, urine, or water. They often change color in response to the presence of certain chemicals, allowing users to quickly determine levels of glucose, pH, or other important indicators. These strips are commonly used in medical settings for monitoring conditions like diabetes or in laboratories for testing water quality. They provide a simple and efficient way to obtain results without the need for complex equipment, making them accessible for both professionals and individuals at home.