A dipstick is a simple measuring tool used to check the fluid levels in engines and other machinery, particularly for oil and transmission fluid. Typically made of metal or plastic, it features a marked scale that allows users to easily gauge the fluid level by inserting and removing it from the dipstick tube. The dipstick can also provide insights into the fluid's condition, such as color and viscosity, which helps identify potential issues. Regularly checking fluid levels with a dipstick is essential for maintaining optimal engine performance and preventing damage due to low or contaminated fluids.