Alt text
alternative textAlt text, alternative text, is the verbal description given to an image in code, read aloud by screen readers and read as content by search engines. It serves two audiences at once: visually impaired users and Google’s image search.
Good to know
Good alt text describes what the image actually shows, in the context it appears in: "Team analysing campaign data in a meeting room" says more than "image1.jpg" or a keyword list. Google also uses alt text to understand the page’s topic.
The accessibility directive obliges many Finnish organisations to provide text alternatives for images. Decorative images get an empty alt attribute so screen readers skip them and users are spared pointless descriptions.
IN PRACTICE
How to write working alt text
Describe content and context
Say what the image shows and why it is on the page. The same image can carry different alt text on different pages, because the context changes.
Forget keyword lists
"Marketing, advertising, social, Helsinki" helps nobody and can hurt. A natural sentence where the term appears naturally is enough.
Mark decoration as empty
Background patterns and mood shots get an empty alt attribute. Informative images, charts and buttons are always described.
PITFALLS
Two ways to write alt wrong
Keywords get stuffed into the description
A term list in alt text is noise to a screen reader user and a manipulation signal to Google. Describe the image, do not optimise it.
Decoration gets described
Verbalising a mood image forces the screen reader user to listen to filler. Decoration gets an empty alt attribute.
FREQUENTLY ASKED
Frequently asked questions
Does alt text affect rankings?+
Yes, in two ways: it is the most important image search signal and helps Google understand the page topic. The effect is small but free.
What do I write for a chart?+
The chart’s conclusion: "Organic traffic grew 140 % in six months." The data belongs in the text, the conclusion in the alt.
Does a logo need alt text?+
Yes: the company name is enough. If the logo links to the front page, "Company, home" works well.
How long can alt text be?+
Usually under 125 characters, because some screen readers cut longer ones. A complex chart gets a longer description in the page text.
How do I audit alt texts on a large site?+
A crawler lists images missing alt text in one run. Fix order: informative images first, decoration with empty attributes last.
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Maintained by the VSCY editorial team · Updated 6 Aug 2026 · Part of the marketing glossary (99 terms)
