Titration is a process of measuring the concentration of an unknown solution by adding a known amount of another solution of known concentration until the reaction between the two is complete. Titration can be used to determine the concentration of an acid or a base in a solution. In acid-base titration, an acid or a base of unknown concentration is reacted with a base or an acid of known concentration, respectively. The reaction between the two solutions is typically monitored using a pH indicator, which changes color as the pH of the solution changes. The endpoint of the titration is reached when the reaction is complete, and the pH indicator changes color. At this point, the amount of the known solution that has been added is used to calculate the concentration of the unknown solution. The equation for an acid-base titration is typically: acid + base → salt + water