Windshield washer fluid, also known as windshield wiper fluid, is a fluid for motor vehicles that is used to clean the windshield with the windshield wiper while the vehicle is being driven. It is a brightly colored liquid that is necessary for safe driving as it helps keep a vehicles windshield clear from dirt, road grime, bugs, and sometimes even frost, depending on the type of fluid used. Washer fluid may sometimes be preheated before being delivered onto the windshield, which is especially desirable in colder climates when a thin layer of ice or frost accumulates on the windshields surface, as it eliminates the need to manually scrape the windshield or pour warm water on the glass.

The most common washer fluid solutions are given labels such as "All-Season", "Bug Remover", or "De-icer", and usually are a combination of solvents with a detergent. The ingredients in washer fluid work together to give you a clean, streak-free windshield no matter how cold it is outside. Most products are made of methanol and other alcohols like ethylene glycol, and many also contain small amounts of ethanol or antifreeze made from methylated spirits to keep the product from freezing during the winter months.

It is important to note that using plain water instead of windshield washer fluid is not recommended as water doesnt have the cleaning power of specialized cleaning fluid for removing bugs, bird droppings, road grime, and other crud that collects on windshields. Additionally, washer fluid is also a lubricant for all the parts involved in the system, and if the reservoir is empty, the pump may overheat and fail, leading to a costly repair.

In summary, washer fluid is a necessary fluid for motor vehicles that is used to clean the windshield with the windshield wiper while the vehicle is being driven. It is a combination of solvents with a detergent and contains ingredients that are meant to clean up stubborn messes. It is not recommended to use plain water instead of washer fluid as it doesnt have the cleaning power of specialized cleaning fluid and can cause damage to the system.