A Neutral Density filter, also called an 'ND' for short, is a filter that acts a bit like sunglasses for your lens and comes in different strengths to block out varying amounts of light from hitting your camera sensor. Doing so is useful for all sorts of reasons, from enabling longer exposures to create movement in water or clouds of a still photograph, or for taming the light when working with video where your shutter speed is often locked.
A Variable ND (VND) filter such as Nisi’s True Color ND-Vario 1-5 Stop Pro Nano has the ability to block out a range of light depending on your requirements so it's a bit more flexible and as it does the job of multiple ND filters it's a more portable option too – no bulky square filters or filter holder needed here.
