Alternative text
Alternative or alt text describes images for users of assistive technology.
If you’re using images that provide meaning or context, you must use alternative text. This means that assistive technology users do not miss out on anything.
Describe the image as clearly and briefly as you can. Do not start alternative text with "an image of" or similar.
If an image is only decorative, such as page dividers or shape graphics then you do not need to provide alternative text.
Follow the guidance on the W3C accessibility website.