A hat protects you from the UV radiation that can cause skin cancer. Many doctors recommend wearing a hat in the summer for those with sensitive skin.
A hat keeps you warm in winter. Around 10% of body heat is lost through the head, assuming no other protection from the cold! So if you are already wrapped up you need to seal off the remaining area to retain warmth.
If you are wearing a hat you will almost certainly not need an umbrella when it rains.
A hat finishes off your outfit, providing a focal point that pulls your whole look together.
A hat expresses your personality better than any other item of clothing. It is the closest to your face, after all. If you are a performer a hat can form part of your stage persona.
A hat is the perfect solution to a bad hair day.
If you are shy a hat can give you confidence. At social gatherings a hat is a proven conversation opener.
Wearing a beautiful hat to an event such as a wedding or a party is a delightful compliment to your hosts.
Buying a new hat is a great morale booster.
