Visual task is the term given to an activity requiring visual perception and located in a certain place (e.g. reading, writing, drawing, computer working). The activity involved can change in the course from day to day. For that reason a variety of visual tasks must be taken into account when planning a lighting system.

The visual task involves certain requirements to be met by the lighting system relating to such factors as Illuminance, Glare Control, Contrast, Uniformity and so on, so that the task can be completed without discomfort or physical hindrance.

Parts 1 and 2 of DIN 5035 describe the criteria to be observed for task-related artificial indoor lighting systems. They also contain provisions for the requirements to be met by artificial lighting systems for specific interiors and activities (service illuminance, color appearance, color rendition class, glare control class).