Multi Coated Filters
Multi coated filters are used to keep glare off of your photographs. Not all filters are multi coated though. Some filters can cause a little glare and light loss because of reflection and this may affect your photos. If your filter is multi coated it can help your camera receive light that isn't reflected.
The filter is layered and coated with a scratch-resistant metallic oxide substance. It is applied to the surface of the lens by a high vacuum process. Just one layer of this coating may be able to cut down on reflection by more than 50 per cent. To reduce the internal reflections throughout the entire spectral range, the filter will need to have several layers of coating.
Some camera manufacturers often make the same filter with or without multi coating, so you need to specify or look for the multi coated version if you want it. Multi coated versions cost more than regular filters but they offer more benefits. They run in price from about $10 to several hundred.