Lens filters are used by photographers to improve or add creativity to their compositions and images. It's recommended that photographers always use UV filters to protect their lenses from scratches, thumbprints, and dust.
There are many different types of lens filters, each for a specific purpose. Filters attach in one of two ways. The most common are circular filters that directly screw onto the lens. The second method is to use a filter holder that accepts universal type rectangular filters. This is useful if you use multiple filters to obtain different effects.