The “Alt” tag is an older HTML coding strategy originally envisioned to compensate for users and browsers not equipped to handle images. And while all of today’s web browsing includes many types of graphics, the alt tag remains an important part of making a site accessible to all users.
An additional benefit is that it provides a semantic description of images for search engines. Google loves this and it has an important impact on SEO. And while alt tags themselves are not a complete SEO strategy, they are one in a number on-page factors that contribute to improved SEO performance.
So here are the basics of using alt text for images.
Keep the tag text short - In general a concise alt tag is best, but it may be important to write a more descriptive tag if the image is important to the context of the article. For example, it may be smart to describe what is happening in the image, or note the author if it was created by a known artist. Just keep in mind that smaller alt tags index in Google’s search more efficiently.
Use the topic of the page in at least one alt text - An alt text is an effective way to tell Google the topic of the page and give it an extra boost in search rankings. Therefore if a page is about Christmas Trees, then it will be of SEO benefit to include an image of a Christmas Tree with alt text as ‘alt= “Christmas Trees”’. That doesn’t mean, however, that it is a good idea to repeatedly use the same alt text. Mix it up and make sure that the alt text is relevant to its associated image.
Stay away from keyword stuffing - Keyword stuffing is considered to be an unethical search engine optimization (SEO) technique, which leads to banning a website from major search engines either temporarily or permanently. Keyword stuffing occurs when a web page is loaded with keywords in the meta tags or in content of a web page. Google’s dislike for keyword stuffing extends to alt text as well, so avoid it. A simple description will suffice and will avoid any Google penalties.
Be precise in alt text for products - For eCommerce sites especially, alt tags should precisely describe the product image so that it shows up in relevant searches. For example. an alt tag that says ‘Mens Lefty Baseball Glove’ is more effective than an alt tag that says ‘Baseball Glove’.
For more great SEO techniques see how to use SEO for membership websites and great strategies for improving SEO for blogs.