Google can’t read images. When you upload an image to your website via your CMS (content management system, such as WordPress), you have the option of assigning an Alt tag. Alt refers to the “text alternative” of an image. The alt tag tells Google what the image is about. This helps Google to confirm that the image is relevant to the page and therefore that the page is even more relevant to the terms it targets; it also helps Google to index your images and display them in Google image search results.