Alt text: what it is and why it matters

What is alt text

Alt text (alternative text, the alt attribute) is a text description of an image added to the HTML <img> tag using the alt attribute:

<img src="seo-audit.jpg" alt="Скриншот результатов SEO-аудита сайта в reChecker" />

Alt text serves three purposes:

1. It is shown to users if an image fails to load
2. It is read by screen readers for people with visual impairments
3. It describes images to search engine crawlers, which cannot "see" pictures

Why alt text matters

Image SEO: Google Images is a significant source of traffic. Without alt text, an image is practically invisible to search engines.

Page rankings: Relevant alt text with keywords strengthens a page's topical relevance.

Accessibility: WCAG 2.1 requires alt text for all meaningful images. Without it, a website is inaccessible to people with visual impairments.

Core Web Vitals: Correct alt attributes help prevent layout shifts (CLS) as images load.

Legal requirements: In some countries (the US and the EU), a website's lack of accessibility may violate the law.

How to write good alt text

Writing guidelines

1. Be specific — describe what is shown, rather than writing "image" or "photo"
2. Include keywords — use them naturally; don't spam
3. 5-15 words long — enough to describe the image, but not too much
4. Don't start with "Image..." — search engines and screen readers already know it's an image
5. Punctuation — a period at the end helps screen readers pause

Examples

Poor:

<img src="img123.jpg" alt="фото" />
<img src="product.jpg" alt="купить товар дешево Москва" />

Good:

<img src="seo-audit.jpg" alt="Анализ SEO-аудита сайта с результатами по скорости и мета-тегам." />
<img src="iphone15.jpg" alt="iPhone 15 Pro в цвете Natural Titanium." />

When alt text should be empty

Decorative images (dividers, backgrounds, icons with no meaning) should have empty alt text:

<img src="divider.png" alt="" role="presentation" />

An empty alt value tells screen readers: "This is a decorative image; skip it."

Alt text for image buttons

If an image is a button or a link, its alt text should describe the action:

<a href="/contact"><img src="contact-icon.png" alt="Перейти на страницу контактов" /></a>

Check alt text with reChecker

Use Image Checker to audit all images on your website. The tool shows:

• Images without an alt attribute
• Images with empty alt text (which may be appropriate for decorative images)
• Alt text that is too long or too short
• The total number of images on the page

FAQ

Do all images need alt text? Yes. The alt attribute must be present on all <img> tags. For decorative images, its value should be empty (alt=""), but the attribute is required.

Does alt text affect rankings in Yandex? Yes. Yandex Images also indexes images and uses alt text to determine what an image is about. Correct alt text increases the visibility of images in Yandex search.

How many keywords should I add to alt text? One or two topically relevant keywords. Don't stuff alt text with keywords — that's spam. Google may penalize over-optimization of alt attributes.