Roughly, this is an infinite-dimensional vector space in which it makes sense to speak of the lengths of vectors and the angles between them; useful examples include certain spaces of sequences and certain spaces of functions.
Classic examples include certain amphibian species in which development is arrested so that the larval form and aquatic habit persist as the organism attains sexual maturity and becomes capable of reproduction.
Examples include certain common infections (e.g., influenza) and atmospheric pollution.
Examples include mammograms, pap smears, colonoscopies, certain blood tests, CDC-recommended immunizations and well child office visits.
Examples include prohibiting or ensuring that certain functions are called, checking access permissions, time or memory constraints, interaction protocols, etc.
Examples include everything from legal case research, certain aspects of journalism, a host of financial services work, and even increasingly some facets of medical diagnosis.
Examples include the drug Herceptin, for women with a certain type of breast cancer, and Gleevec, for a type of leukemia and a rare gastrointestinal cancer.
Examples include creating or solving something or achieving a certain level of expertise or responsibility.
Examples include the lactose- and galactose-utilization systems in certain bacteria, such as Escherichia coli and Streptococcus.
Other examples include cardiac stents for cases of mild chest pain and certain procedures for back pain.
Paradigm examples include the pleasure derived from delicious food or the awfulness of certain bad smells.
