The Liquid Limit is a measure used in soil mechanics to determine the water content at which soil changes from a plastic state to a liquid state. It is an important property of fine-grained soils, such as clay, and helps engineers assess soil behavior under varying moisture conditions. To find the liquid limit, a standard test is performed using a device called a Casagrande apparatus. The soil sample is placed in a cup, and a groove is made in the soil. The liquid limit is reached when the groove closes after a specified number of blows, indicating the soil's transition to a liquid state.