A neutral density filter (ND filter) is a photographic accessory that reduces the intensity of light entering a camera lens without affecting the color of the scene. This allows photographers to use wider apertures or slower shutter speeds in bright conditions, enabling creative effects like shallow depth of field or motion blur. ND filters come in various strengths, measured in stops, which indicate how much light is blocked. They are commonly used in landscape photography, videography, and other situations where controlling exposure is essential. By using an ND filter, photographers can achieve desired effects while maintaining proper exposure settings.