The market for cell phones, particularly in the context of the dominance of Apple and its iPhone, is best described as having an Oligopoly structure.
In an oligopoly, a few large firms dominate the market, and they hold significant market power. In the smartphone market, companies like Apple, Samsung, and a few others are key players, each offering differentiated products. This leads to limited competition, distinct branding, and the ability to influence prices, which characterizes an oligopolistic market rather than a monopoly (where one firm controls the entire market), monopolistic competition (many firms with some differentiation), or perfect competition (many firms with homogenous products and no market power).