What should the alt text of an image describe?

The alt text of an image serves an essential purpose in web development and accessibility. It is meant to provide a text description of the content and function of the image, which is crucial for users who may not be able to see the image, such as individuals using screen readers due to visual impairments. By describing what the image depicts rather than its technical details or physical attributes, alt text ensures that all users can understand the context and meaning that the image conveys.

This practice aligns with web accessibility guidelines, which emphasize the importance of making web content available to all users, regardless of their abilities. Therefore, providing an accurate and descriptive alt text improves the overall user experience and supports inclusivity on the web. The other choices, such as the image source URL, size, or technical specifications, do not address the primary role of alt text in conveying the intent or meaning of an image to the audience.