Generally, plants require either sunlight, bright light, medium light or low light. Unfortunately, these terms aren't always used. Looking through a few sources you will find light levels called shady, filtered, intense, indirect, or reflected. To make it even more confusing, the definitions of each light level can vary quite a bit. Everyone who writes a book or sells plants has their favored terms for light levels and definitions for each.
More exact information is available, based on a measurement called footcandles.
Since few people have access to a light meter, we rely on descriptions. Keep in mind that all light descriptions are based on the amount of light available in the summer. Plants that need at least 4-5 hours of direct sunlight and bright light the rest of the day are classified as sun plants. This term describes the most light available without any direct sun. Large north facing windows and areas several feet away from a sunny window are bright light, as are areas where the sunlight is diffused by a sheer curtain.