Alt text is the short line of copy attached to an image in your website’s code, and it does two jobs at once. It tells screen readers what the image shows for visually impaired visitors, and it tells Google what the image is about since search engines cannot actually see pictures. Get it right and you pick up a small but steady stream of image search traffic, better accessibility scores, and a bit of extra context that helps the rest of your page rank. Get it wrong and you are either leaving it blank or stuffing it with keywords, both of which waste an easy win.
What Alt Text Actually Does
Every image tag on your site can carry an alt attribute. When it loads properly you never see it, but when an image fails to load, or when someone is using a screen reader, that text is what appears instead. Google’s own crawlers read this text as one of the few clues they get about what an image contains, alongside the file name and the surrounding page copy. If you run a PPC marketing agency style account and also care about organic visibility, this is one of those rare jobs that benefits paid and organic performance at the same time, since ad platforms and search engines both reward clear, well labelled creative.
I once audited a client’s ecommerce site where every single product photo had alt text reading “IMG_2841” or nothing at all. We rewrote around 400 of them over a fortnight, and within two months their Google Images traffic had roughly tripled. Nothing else changed on those pages. It is one of the few bits of technical SEO where the effort to result ratio is genuinely lopsided in your favour.
Writing Alt Text That Actually Helps
Keep it short, specific, and honest about what is in the picture. Describe the image the way you would to someone on the phone who cannot see it. Skip phrases like “image of” or “picture of” since screen readers already announce that it is an image. And never cram in a list of keywords hoping to catch extra rankings, because that reads as spam to both users and Google.
| Situation | Weak alt text | Better alt text |
| Product photo | “shoe” | “Men’s brown leather brogue, size 9” |
| Blog header image | “” (left blank) | “Marketer reviewing a Google Ads dashboard on a laptop” |
| Purely decorative graphic | “background pattern design” | “” (empty, marked decorative) |
| Infographic | “seo tips infographic” | “Five step checklist for on page SEO in 2026” |
| Logo in footer | “logo” | “Flow20 company logo” |
That last row matters more than people think. Decorative images, dividers, and background flourishes should have an empty alt attribute rather than a forced description. Screen readers skip past empty alt text automatically, but if you leave it out entirely, some readers announce the file name instead, which is a genuinely poor experience for the person listening.
Where This Fits Into Wider SEO
Alt text on its own will not fix a struggling website, but it sits alongside other on page basics like page speed, headings, and internal linking as part of proper SEO services. If you are already running a Google Ads agency in London style setup and pushing traffic to landing pages, the same image discipline applies there too, since ad platforms increasingly reward accessible, well structured pages with better quality scores. The same goes for social creative. If your team runs a social media advertising agency style operation, or manages campaigns through a Facebook ads agency in London, alt text on any images embedded on your site still counts even if the ad creative itself sits on the platform.
A quick checklist worth keeping on hand:
- Describe what is genuinely in the image, not what you wish it said
- Keep it under around 125 characters where you can
- Leave alt text empty for purely decorative images
- Never repeat the same keyword across every image on a page
- Update alt text when you swap out an image, not just the file
FAQs
Does alt text still affect SEO in 2026?
Yes, though its weight is modest compared with content quality and page experience. It remains one of the clearest signals Google has for understanding what an image shows, and it directly affects whether that image can rank in Google Images.
What is the difference between alt text and a title tag on an image?
Alt text describes the image for accessibility and search engines. The title attribute shows a small tooltip when someone hovers over the image, and it carries far less SEO weight, so alt text should always be your priority.
Should every image on a page have alt text?
Every meaningful image should. Purely decorative ones should have an empty alt attribute rather than none at all, so screen readers know to skip them cleanly.
Getting This Right Across Your Whole Site
If you have hundreds or thousands of images sitting with blank or lazy alt text, this is a job that pays for itself quickly once it is done properly. Get in touch with the Flow20 team and we will run an audit of your current image tagging as part of a wider look at your on page SEO.
