Conventionally, hair is straightened using a flat brush and a blow dryer but by the end of the night (unless you've already been caught in a rain shower in which case your hair will already be looking like a frizz ball) your hair will have resigned from its unnatural straight state and return back to your original hairstyle.
However, all is not lost as there's a new hair straightening method out there which will completely change your life. Originated in Japan, this method uses heat to change the shape of your hair. After the cuticle is broken down with chemicals, all curls and kinks are ironed straight with a hot iron. A neutralization process then closes the cuticle, causing hair to stay straight.
The results from the process are amazing, considering your hair is subjected to nearly 6 hours of chemical and heat treatment. It is advisable to give your hair a lot of care and attention post treatment by using special after care products which can be found online or in most beauty spas and salons. However, all the time and effort is worth it, as your hair will not need to be treated for at least 6 months. So twice a year should be enough for curl free hair all year.