Habitat is a fundamental concept for understanding and conserving nature, yet it remains one of the most confusing terms in ecology. Traditionally, it refers to discrete, uniform environmental units–a notion familiar to both scientists and the general public. Since the early 1990s, interest in the habitat concept has grown, particularly with the emergence of the resource-based habitat (RBH) concept, first described for butterflies by R.L.H. Dennis in 1996. Dennis’s work on the RBH concept was later recognized with the British Ecological Society Book Award in 2012, highlighting its significance and impact on ecological thinking. An RBH is defined as the geolocated set of resources and conditions sufficient to support a population or cohort of a species. It includes all the essential resources and conditions that an individual uses or experiences throughout its life. This approach reveals that many species occupy multiple traditional habitats, challenging our understanding of their environmental preferences, distribution and abundance. A core principle of the RBH is that each individual has a unique RBH, reflecting its specific needs and behaviours. Thus, to determine a species’ RBH, scientists must analyse variation across a representative sample of individuals. Understanding a species’ RBH across a region–or throughout its range–requires sampling at multiple sites to capture variation in resource use and environmental tolerance. The RBH concept is not intended to replace the traditional concept, which remains valuable–especially in relatively uniform landscapes and for community-level conservation. Although originally developed for butterflies, the RBH concept is applicable to all organisms, including humans. The application of the RBH concept to all life forms may provide novel insights into our understanding of species biology and community characteristics. Ultimately, the RBH concept highlights the importance of sampling and analysing variation, offering a more detailed and flexible framework for understanding species’ ecological relationships.