An ornamental cloth hung above a throne or a bed, originally made of fabric held up by poles or draped softly between posts at the four corners of a bed (see baldachine, tester). Canopy now encompasses a much broader meaning, including any type of overhead covering.
Whilst bed canopies are often still decorative, with pleated and gathered silks and soft cottons within a framework, they can also be as simple as a piece of fabric draped between two ceiling hung poles.
Outdoor canopies are essentially practical and again can be extremely simple in design and in execution–something more like a sail that can be rolled or folded back, made of cotton or any waterproof fabric, hung from a wall, posts or even trees, so long as it adequately fits the elemental criteria: to shield from sun and rain.