Learning the alphabet is the first step to becoming a great writer. Learning basic lighting setups with just one key light is essential for every photographer taking their first steps in portraiture.
In this video, Pye Jirsa describes in detail how you can achieve each of these lighting techniques. He also shares a little history and where these lighting patterns are mostly used, but do not assume if you don't shoot fashion, for example, you can't use butterfly lighting. These setups are not reserved solely for one area of photography. I appreciate the fact Jirsa explained how the fill light affected the perception of the portraits in terms of drama. Although the split light is often thought of as very dramatic lighting, with the right amount of fill, you can create a beautiful and pleasing portrait.
The Paramount lighting, or the butterfly pattern, was often used in the old movies, because they used hard light almost exclusively. Placing the light this way made the face look good without weird "double nose" shadows. One of the reasons behind that was the lower sensitivity of the cameras back then, because any diffusion of the light source would cut the power of the illumination. Another reason was the trend of making faces of actors look distinct from the natural way of perceiving the people around us. Despite being such an old style, it is still used today and looks gorgeous.