A mobile friendly button is characterized by several key features: 1. Size: The button should be large enough to be easily tapped with a finger. A minimum size of 44x44 pixels is recommended. 2. Spacing: Adequate spacing around the button prevents accidental clicks on other elements. 3. Contrast: High contrast between the button and its background makes it stand out. 4. Text: Clear and concise text on the button ensures the action is easily understood.