Which attribute in the <img> tag specifies alternative text for users?

The alt attribute in the tag is essential for accessibility and usability. It provides alternative text that describes the image when it cannot be displayed for any reason, such as a slow internet connection, or when the user relies on a screen reader due to visual impairments. This ensures that users still receive a context or meaning from images, improving their overall experience on the website.

Using the alt attribute is not just about providing information for those who cannot see the image; it also plays a significant role in search engine optimization (SEO) by helping search engines index images properly. Furthermore, in HTML5, it's a requirement for the tag, making it an integral part of web standards for accessibility.

In contrast, the title attribute is often used to provide additional information when users hover over an element, but it is not a substitute for alt text and usually does not serve the same function as the alt attribute. The src attribute is necessary for specifying the path to the image file, and the href attribute is used within anchor tags to specify a link, neither of which conveys any alternative text for the image itself.