Some still use uv or clear filters but there is rather a debat over their usefullness in protecting a lens. Lens hoods usually do a good enough job unless you are in sandy/windy conditions.
Think about how much technology and science went into grinding that precision glass for your lens. Why put something over it and expect as sharp of a picture.
Necessary sometimes but I've learned from here and other research...don't buy cheap filters. Just going to degrade your photos.