What attribute is used to specify an alternate text for an image?

The attribute used to specify an alternate text for an image in HTML is the "alt" attribute. This attribute serves an essential function: it provides a text description of the image for users who are unable to view it, whether due to visual impairments or because the image fails to load. Having alternative text is important for accessibility, ensuring that all users can understand the context or content of the image.

For example, if an image cannot be displayed, the alt text will be shown in its place, allowing users to gain some understanding of what was intended to be shown. Additionally, search engines and web crawlers use this attribute to index the image, further emphasizing its importance in both usability and SEO practices.

The other attributes mentioned don't serve the same purpose as the alt attribute. The "src" attribute is used to specify the source URL of the image, while "title" may provide additional information that appears when a user hovers over the image, but it does not serve as an alternative text. "Description" is not an HTML attribute related to images. Therefore, the "alt" attribute is the correct choice for providing alternative text.