A reagent is a substance or compound that is added to a system to cause a chemical reaction or to test for the presence of another substance. Reagents are commonly used in laboratories for various experiments, including chemical analysis and synthesis. They can be in the form of solids, liquids, or gases and are essential for conducting reactions in fields like chemistry and biochemistry. In many cases, reagents are used to identify specific compounds or to facilitate reactions between different substances. For example, in a titration process, a reagent is added to determine the concentration of a solution. Understanding how reagents work is crucial for scientists and researchers in developing new materials and conducting experiments.