A trend is a line of general direction of movement, a prevailing tendency of inclination, a style or preference, a line of development, or the general movement over time of a statistically detectable change. In a few words, "trend" is a synonym to "tendency".

A fad is a practice or interest followed for a time with exaggerated zeal. The nature of fad is individual. It could be called as a like in a guy an individual/individual society's over interest in some thing which is considered to have consist of some virtue i.e. fad diet, exercise etc. The benefit of something considered as fad may not have been scientifically verified or it may lack the rational proof.

A craze is a product, idea, cultural movement, propensity or model that gains popularity among a small section of the populace then quickly migrates to the mainstream. Crazes are characterized by their lightning fast adoption and swift departure from public awareness. Being of temporary nature is one of the major characteristics of craze. Crazes and fads are also characterized by their unusually high interest and sales figures relative to the time they are active in the marketplace, as compared with other similar products, ideas, cultural movements or models.