Curtains in general come in all styles, shapes, colors, and types. Some of these types are better suited to be bathroom window curtains than others. This is a very basic guide to the most popular types of curtains that are either suited for bathroom use or can be altered slightly to be suited for bathroom use.
Pinch Pleated curtains are a very traditional style that has remained very popular. Basically they are curtains that have pleats permanently stitched into then, then the pleats are pressed together with a stiffener material at the top. The style is usually embellished with tiebacks to keep the curtains open. Typically they do run the whole length of the window, so this will not be good for bathrooms if your window sits right above the shower as the bottom of the curtains will likely get wet.
If you are planning your bathroom window curtains to be in a bright attention drawing color, then grommet top curtains might be right for you. They are curtains with round grommet holes in the top with a decorative curtain rod to match. This is a very popular style right now, so you will find that they are available in many colors, sizes, and patterns. These are perfect for a bathroom since they are so low maintenance. They do not require drapery pins, and can be removed for cleaning very easily.
Rod pocket curtains are also a casual, but elegant style that can easily be used for bathroom window curtains. Just be sure that you don’t use a wooden rod, since you are dealing with a damp, wet bathroom setting. These curtains have a pocket of material that is slid onto the curtain rod and set in place. It is very simple and looks very elegant when paired with the right fabric. A good bonus for this type of curtain is that the curtain rod will be minimally exposed, so you can get something very basic and not that decorative, and no one would be any the wiser.
Flowing drapes are also a great, casual style for bathroom curtains. The key to bathroom curtains is simple, but elegant. This style has no pleats, folds or pockets. It is suspended with rings off the curtain rod and droops in between those rings. This gives it the most distinctive style. Keep in mind that it does lose the drooping effect when the blinds are closed but is just as elegant because of the decorative curtain rod and drapery rings.