Image alt text, or alternative text, is a written description of an image that helps users understand its content. It is primarily used by screen readers for individuals with visual impairments, allowing them to comprehend what the image represents. Alt text is also beneficial for search engines, as it helps improve the accessibility and SEO of a webpage. When creating alt text, it’s important to be concise and descriptive. For example, instead of saying "dog," a better alt text would be "a golden retriever playing fetch in a park." This provides more context and enhances the user experience for those who cannot see the image.