Online marketing map and termsThe alt tag (alternative text field) on images can be used to provide users information and helps search engines determine the content of a page. Alt tags are therefore useful for SEO and browsers yet are often overlooked.

When you post content on the web, you need to make it as findable as possible. The alt tags in the image field help search engines to do this.

You can locate your alternative text field in the upload image section of your CMS. Typically it is a small, elongated box underneath the captions field. Ideally the alt tag text should be a quick sentence describing what the image is.

Improving user experience

Not only does text in an alt tag field support search engine crawlers to categorise and index your page, it also enhances the experience of the user. Well written alternative text offers specific information to readers either to recap a point in the article or as an aid to highlight a point you want to make with visuals.

Not only that, but screen readers used to help internet users with visual impairments and cognitive disabilities translate information on-screen recognise alternative text and can describe the image to the user.

The text is also displayed in browsers, so if mobile users have chosen not to display images, they can still have an understanding of what images do appear on the page. Likewise if the image does not load due to low bandwidth whilst visiting your page.

You also benefit from update the alt tags as your page appears in image searches and is more accessible across a wider range of platforms. You can also use different keywords to give your products more exposure.

How to write alternative text

The alt tag field is not very big so you must keep your snippet brief. Your target is to stay under 50 characters so thinking of suitable text can be more difficult than an engaging tweet. Ideally include at least one keyword.

The information you provide in the alt tag must be relevant to the image – and not just the article. It helps if you start with the most relevant words, ideally the keyword. Also keep alternative text search friendly.

If you have included a caption on the image, do not repeat the same text in your alt tag as this is classed as duplicate content by search engines. It is much better to enter a brief description of what the image is.

The use of images for SEO and visibility should not be underestimated – and nor should tagging images with appropriate text.