Alt text, also known as alternative text or the alt attribute, is the descriptive text written inside the alt attribute of an image in HTML. If an image on a web page cannot be loaded for any reason, the browser may show the alt text instead of the image. People who use screen readers can also understand what an image represents through alt text. For this reason, alt text is important not only for SEO, but also for accessibility and user experience.
The main purpose of alt text is to describe the meaning and function of an image in a short, clear and contextually relevant way. If an image is not purely decorative and carries information within the content, the alt text should communicate that information in text form. For example, if a product image, chart, icon, infographic or explanatory photo provides meaning to the user, that meaning should be accurately reflected in the alt text. This ensures that users who cannot see the image do not miss important information on the page.
From an SEO perspective, alt text can help search engines better understand the image and the context of the page it appears on. Search engines may evaluate not only the file name or surrounding text, but also the alt attribute when interpreting images. For this reason, alt text is especially important for e-commerce, publishing, blogs, product listing pages, portfolios and visually rich websites that want to gain image search traffic. However, alt text should not be used as a place for keyword stuffing.
The most important rule when writing alt text is that it should genuinely describe the image. What appears in the image, why it matters to the user and how it relates to the page context should all be considered. For example, writing only “shoe” for an image of a sports shoe is often too vague. A more descriptive alt text such as “black lace-up men’s sports shoe” makes the image more meaningful for both users and search engines.
In HTML, alt text is usually used inside the <img> tag. For example, in <img src="shoe.png" alt="Black lace-up sports shoe">, the phrase “Black lace-up sports shoe” is the alt text of the image. The src attribute defines the source of the image file, while the alt attribute defines the image description. These two fields have different functions. The image file name, title attribute and alt text are not the same thing.
Alt text should also not be confused with the image title. The title attribute may show additional information in some cases when a user hovers over the image, but it does not replace alt text for accessibility or SEO. Alt text plays a more critical role when the image fails to load or when a screen reader needs to describe the image. For this reason, adding only a title is not enough; meaningful images should have appropriate alt text.
Good alt text should be short, descriptive and natural. Depending on the context of the image, a few words or a short sentence may be enough. Unnecessary details, repeated phrases and keyword lists should be avoided. For example, “shoe, sports shoe, black shoe, men’s shoe, affordable shoe” is not a natural alt text. A clear description such as “Black lace-up men’s sports shoe” is a healthier option.
When writing alt text, phrases such as “image,” “picture” or “photo” are often unnecessary. Screen readers can already indicate that the element is an image. Therefore, “Photo of a black lace-up sports shoe” can usually be simplified to “Black lace-up sports shoe.” However, if the type of visual is important for understanding the content, words such as “infographic,” “screenshot,” “map” or “chart” can be used.
On e-commerce websites, alt text should be consistent with the product description. If the product’s colour, model, type, use case or distinctive feature is clearly visible in the image, it can be included in the alt text. For example, descriptions such as “White leather women’s sneaker side view” or “Grey three-seat sofa with wooden legs” provide more context. However, irrelevant campaign phrases, unnecessary price expressions or repeated category keywords should not be inserted into alt text.
Decorative images should be handled differently. If an image does not carry information, is used only for design purposes or does not provide meaningful content for the user, an empty alt attribute can be used. For example, alt="" helps screen readers skip decorative images. This reduces unnecessary information and improves the accessibility experience.
The context of the page where the image appears should also be considered when writing alt text. The same image may carry different meanings on different pages. For example, a shoe image may describe the product itself on a product page, while it may support a “graduation outfit ideas” context in a blog article. Therefore, alt text should reflect not only the object visible in the image, but also the function of the image on the page.
For image SEO, alt text alone is not enough. File name, image size, compression, suitable format, responsive image usage, lazy loading settings, page speed, surrounding text and the position of the image on the page also matter. For example, using a descriptive file name instead of “IMG_1234.png,” optimizing the image and ensuring that the page loads quickly all contribute to a stronger image SEO structure.
One of the most common mistakes in alt text usage is writing the same or very similar description for every image. If a page contains many product images, each image should describe its distinguishing feature whenever possible. Instead of repeating “sports shoe” for every image, descriptions such as “Black lace-up sports shoe front view,” “Black lace-up sports shoe side view” or “Sole detail of black sports shoe” can be more meaningful.
In summary, alt text is the descriptive text of an image in HTML, and it is important for accessibility, user experience and SEO. It provides information when an image fails to load, helps screen readers interpret the image and gives search engines contextual signals about the image. Good alt text should be concise, descriptive, natural, contextually relevant and user-focused. It should not be used for keyword stuffing, but to communicate the real meaning of the image.
