The ecological niche of an organism, species or population describes how they respond to and alter environmental factors, known as niche dimensions, within an ecosytem. The dimensions of a niche depend on the type of ecological niche and can range from physical environmental conditions such as temperature, soil pH, and soil composition to interactions between species such as competition and predation. The dimensions can also include how they alter the environment and fulfill a role important for the survival of other species, such as recycling nutrients.

Two main types of ecological niches include the fundamental niche and the realized niche. The size and shape of ecological niches can be quantified and visualized using n-dimensional hypervolumes. The boundaries and limits of each fundamental niche dimension can be carefully determined experimentally.