The twice-yearly global schedule of New York, London, Milan and Paris shows is usually called fashion month.
Fashion month generally refers to the main runway circuit for the autumn/winter and spring/summer ready-to-wear seasons. The four major cities stage their shows in succession, creating a concentrated period when designers present new collections to buyers, editors and international media.
The phrase describes a cycle, not one single event or organization. Each city retains its own fashion week, calendar and governing bodies, while the sequence allows the wider industry to follow the collections across continents.
Fashion month can be confusing because designers also show resort, pre-fall, couture and menswear collections on different schedules. Digital presentations and independent calendars have further diversified the system, but the traditional women’s ready-to-wear circuit remains the best-known use of the term.