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

The alt attribute is used to specify an alternate text for an image in HTML, which serves multiple important functions. When an image cannot be displayed, the text provided in the alt attribute is shown in its place. This helps improve the accessibility of web content, as screen readers can read this text aloud to users who are visually impaired, conveying the purpose or content of the image. Additionally, search engines use the alt text to understand the content of images, which can enhance search engine optimization (SEO) for web pages.

The other attributes mentioned do not serve this purpose: the title attribute provides additional information about an element, the src attribute specifies the source URL of an image, and the href attribute is used for linking to other web pages or resources.