Which CSS property is used to change the font of an element?

The CSS property used to change the font of an element is the font-family property. This property allows you to specify the typeface that will be used to render the text within the selected element. By using font-family, you can define a specific font, or a list of fallback fonts, ensuring that text displays using a preferred style if it is available on the user's system.

Using font-family not only allows for aesthetic choices in web design but also enhances readability and user experience. Fallback fonts are critical for maintaining design consistency across different devices and browsers.

The other properties listed serve different functions: text-style is not a valid CSS property; font-weight is used to set the weight (boldness) of the font, and font-size adjusts the size of the text, but none of these directly change the typeface. Thus, font-family is the correct choice for altering the font of an element.