A flat iron is a hair styling tool used to straighten hair. It consists of two flat plates that heat up and are pressed together to smooth out curls and waves. Flat irons come in various sizes and materials, such as ceramic, titanium, and tourmaline, which can affect how quickly they heat up and how evenly they distribute heat. Using a flat iron can help achieve a sleek and polished look, making it a popular choice for many people. To use a flat iron safely, it's important to apply a heat protectant spray to the hair and adjust the temperature according to the hair type, ensuring minimal damage.