An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation. Adaptations contribute to the fitness and survival of individuals. Organisms face a succession of environmental challenges as they grow and develop and are equipped with an adaptive plasticity as the phenotype of traits develop in response to the imposed conditions. The developmental norm of reaction for any given trait is essential to the correction of adaptation as it affords a kind of biological insurance or resilience to varying environments.

The significance of an adaptation can only be understood in relation to the total biology of the species.

— Julian Huxley

Adaptation is, first of all, a process, rather than a physical part of a body. An internal parasite (such as a fluke) can illustrate the distinction: such a parasite may have a very simple bodily structure, but nevertheless the organism is highly adapted to its specific environment. From this we see that adaptation is not just a matter of visible traits: in such parasites critical adaptations take place in the life-cycle, which is often quite complex. However, as a practical term, adaptation is often used for the product: those features of a species which result from the process. Many aspects of an animal or plant can be correctly called adaptations, though there are always some features whose function is in doubt. By using the term adaptation for the evolutionary process, and adaptive trait for the bodily part or function (the product), the two senses of the word may be distinguished.

Abel Tesfaye (born February 16, 1990), better known by his stage name The Weeknd, is an R&BCanadian recording artist and record producer from Toronto. He began recording songs under The Weeknd and uploading them to YouTube in late 2010, though the identity of the individual behind the project was initially unknown. In March 2011, The Weeknd released a nine-song free album, House of Balloons which was critically acclaimed. The title track is based on a sample of Siouxsie and the Banshees' hit single "Happy House. The first album is a part of a trilogy which includes Thursday released in August of the same year and Echoes of Silence issued in December. In June, House of Balloons was named as one of ten shortlisted nominees of 2011 Polaris Music Prize but eventually lost to Arcade Fire's The Suburbs. On December 21, 2011 at 11:07 p.m. EST Tesfaye released his highly anticipated third mixtape Echoes of Silence. The Weeknd's site crashed shortly after due to the large number of downloads. The Weeknd quickly provided a Hulkshare link to keep the album available while the official site was down.