From the French word for veil, it is indeed a fine, lightweight, semi-transparent fabric, that serves to filter light, moderate a view or to create an element of privacy.
Voile was historically made of cotton, linen or a cotton/linen mix, but can also be made of silk, wool, bamboo , polyester or mixes, and in many colours. The twisted yarns used in plain weave allow the fabric to reflect light, and lends it a sense of movement.
Voile can be used for sheer bed drapes, table linen, cushions, mosquito nets undercurtains, blinds and curtains . It’s important to choose a readily washable material, either a cotton or a polyester that looks and feels like cotton for urban under curtains so that they can be washed and re-hung on the same day.