In Plain English
Alt text is like briefly describing an important picture to someone over the phone: include what they need from it, not every visible detail.
Why it matters
Understanding alt text helps you make clearer SEO decisions without mistaking one signal or metric for the whole picture.
Example
A product image might use alt text such as “Red insulated water bottle with a loop lid.” A decorative flourish can use an empty alt attribute.
Common misunderstanding
Alt text primarily supports accessibility. It should be contextual and concise, not stuffed with keywords or added to decorative images for SEO.