A photo on a website does two jobs at once: it shows something to a sighted visitor, and it provides information to search engines and to visitors using assistive technology, if it's set up correctly. Most small business sites only handle the first job and skip the second entirely.
Alt text isn't optional decoration
Alt text (alternative text) is a short description attached to an image, invisible in normal browsing but read aloud by screen readers and used by search engines to understand what the image actually shows. An image with no alt text, or generic alt text like "image1," provides none of that information to either audience.
Write alt text that describes the actual content
A good alt text describes what's genuinely in the photo, specifically: "Finished kitchen remodel with white shaker cabinets and quartz countertops" rather than "kitchen photo" or, worse, nothing at all. This helps a screen reader user understand the page and gives search engines real context about the image's relevance to the page's topic.
File names matter too, in a smaller way
A file named "IMG_4821.jpg" carries no information. Renaming it to something like "bathroom-tile-installation-tulsa.jpg" before uploading gives search engines one more small, honest signal about what the image shows and where the work was done.
Don't stuff keywords into alt text
Alt text should describe the image accurately, not become a place to cram extra keywords that don't actually describe what's shown. Overstuffed, inaccurate alt text can read as manipulative to search engines and is actively unhelpful to a screen reader user trying to understand the page.
This connects directly to accessibility
Alt text is also a core requirement for website accessibility more broadly, not just a search optimization tactic. See website accessibility basics for small business for the wider picture.
Questions
Do I need alt text on every single image?
Purely decorative images (a background texture with no informational content) can have empty alt text on purpose, which tells screen readers to skip them. Any image conveying real information needs real alt text.
How long should alt text be?
Long enough to accurately describe the image, typically one concise sentence. It doesn't need to be exhaustive, just accurate and specific.
Does this actually affect image search rankings?
Yes, accurate alt text and file names are among the signals Google's image search uses to understand and rank images, on top of their accessibility value.