Concave and convex lenses are curved lenses that bend light in a predictable manner depending on their radius of curvature and index of refraction. A concave lens bend inwards and a convex lens bends outwards.
Convex bulges outward (thicker in the center than the edge)Concave bulges inward (thinner in the center than the edge)Convex lenses magnify when you look through then, concave lenses make things look...
Both concave and convex lenses are used in glasses; A microscope, like a reflecting telescope, uses a concave mirror, a plane mirror, and a convex lens; A refracting telescope uses two convex lenses...