Alt text (alternative text) is the written description of an image provided in the HTML img tag. It serves two critical purposes: it allows search engines to understand what an image depicts, and it provides a text alternative for users who cannot see the image — including people using screen readers and those with slow connections.
For AEC firms, project photography is central to the website experience, yet alt text is frequently missing or unhelpful. Instead of leaving alt text blank or writing "photo1.jpg", a well-written alt text might read: "Exterior view of the riverside community centre in Bristol, completed 2023". This describes the subject, context, and recency.
Image alt text also contributes to Google Image Search rankings. Firms with well-described project imagery can attract traffic from clients searching for specific building typologies or project types in their region.
Alt text should be concise — typically under 125 characters — and should describe what is actually in the image. Avoid keyword stuffing in alt text, as this is flagged as a spam signal by modern search algorithms.