We all get frizzy hair at times, but some people are more prone to frizz than others. Certain factors can make frizz worse, so knowing what causes frizz is the first step in combating it. Frizz is usually the result of dry hair. When the hair is dry, it tries to absorb moisture from its surroundings, which causes individual cuticles to swell instead of lying flat. A microscopic view of your cuticle, or outer shell of your hair shaft, will normally show overlapping scales. When hair is seeking moisture, the scales separate and even rise. For this reason, people often complain of frizzy hair in hot, humid weather: it is because their dry hair is doing whatever it can to soak up the moisture in the air.
If you want to get smoother hair, you have to start by moisturizing your hair correctly.