While compressing your images is step one for website performance, it's not the only thing search engines care about. Google relies on context clues to understand what an image depicts. Here is how to master file names and alt text to boost your SEO traffic.
Uploading an image named IMG_8473.JPG is a massive missed opportunity. Search engines read file names to understand the subject matter. Before you upload or compress, rename your file to something descriptive and keyword-relevant, like vintage-leather-jacket.jpg.
When naming your files, always use hyphens (-) to separate words, not underscores (_). Google's algorithm treats hyphens as word separators, but it merges words connected by underscores. For example, black-shoes.jpg is read as "black shoes", while black_shoes.jpg is read as "blackshoes".
Alternative text (Alt text) is an HTML attribute applied to image tags. Its primary purpose is web accessibility—screen readers use it to describe images to visually impaired users. However, it also acts as a massive direct ranking factor for Google Images.
Keep your alt text specific, concise, and natural. Don't blindly stuff it with keywords. If your image is a picture of a dog playing fetch, your alt text shouldn't be "dog puppy cute pet buy dog food". It should simply describe the image: "Golden Retriever catching a tennis ball in a park".
Search engines also look at the text immediately surrounding the image to gather context. Make sure your properly named and tagged image is placed near relevant HTML headings and paragraphs on your page to reinforce its meaning and boost its ranking power.