An umbrella includes a supporting frame, an umbrella frame supported by the supporting frame, an umbrella awning, and a functional module. The umbrella includes a guiding arm, an upper hub securely coupled at a top end of the guiding arm, a plurality of awning arms radially and pivotally extended from the upper hub, and an awning cap detachably coupled on the upper hub. The umbrella awning is supported by the awning arms to define a shading area under the umbrella awning, wherein a center portion of the umbrella awning is securely sandwiched between the upper hub and the awning cap to retain the umbrella awning in position. The functional module is detachably coupled on the awning cap for providing an additional function of the umbrella.