Image alt attribute

• Alt text describes the content of the image and provices a text-alternative.
• Good alt text is short but descriptive, and meant to briefly convey the meaning of the image.
• For images, screen readers can access the alt attribute and read its contents to deliver key information.
• Per HTML5 specification, this is now considered mandatory.
• alt can be set to an empty string when images are grouped with a caption already describing them, or are used for decoration only.

<img src="visualDecoration.jpeg" alt="">

参考资料：

• Add a Text Alternative to Images for Visually Impaired Accessibility
• Know When Alt Text Should be Left Blank