Alt text, technically known as alt tags, are snippets used in HTML code that describe the appearance and function of an image on a page. Alt tags have 2 primary functions:

• Accessibility; to describe images to those with a visual impairment so that they can appreciate the content on your site and have the same user experience as those who do not have a visual impairment. 
• SEO; Google crawlers, although are extremely advanced, cannot physically see images so by implementing alt tags you are able to describe what the image is using relevant keyword search terms to drive traffic to your website. 

The Importance of Alt Tags

Now we understand the two purposes of alt tags: they hold great importance for both technical and legal requirements. 

If your website does not meet certain design standards and is not accessible to disabled users then you can be sued for discrimination. For those with disabilities such as sensory loss or mobility problems, the internet is a place of convenience for home shopping and grocery deliveries. Thus, it is fundamental that your website is accessible for all as so many people rely on the internet to complete everyday tasks and live their lives without any discrimination or prejudice. 

From a technical perspective, as briefly discussed, alt text is extremely beneficial for SEO and improving your SERP. If you have alt tags on your images, videos and voice clips you will be able to target highly searched keywords and make these images readable for crawlers. For example, this is an image of an employee from Shepherd Roofing and Slating standing in front of the company van:

Google may just see this image as ‘man standing in front of a van’ and not take into account it’s an image of a branded van for a company offering a service. However, if you are trying to rank for something along the lines of ‘professional roofing and slating company Fife’ then you must implement alt tags which include these keywords. Alt tags provide you with the opportunity to include and target keywords in addition to including on-page keyword targeting and thus, increasing your chances of ranking. 

How to Write a Good Alt Tag

It’s all very well to understand and appreciate the importance of alt text, however the key to success is recognising what makes a good alt tag and what can have a negative impact when deploying alt tags on your images. The code for alt texts looks like the following in HTML: 

• <img alt=”text alternative”>

It is important to note that when deploying alt tags every <img> must have an alt= attribute to ensure that crawlers are able to read and understand the code to best rank your website. When writing good alt text there are another few factors you must consider to ensure you are optimising your website as best as possible: 

• Describe the image as specifically as possible; alt text is primarily there to provide text explanations of images so you must ensure that you are truly describing the images on your site and not just trying to target keywords.
• Keep it short and to the point; the most popular screen readers cut off alt text at around 125 characters so be sure to keep everything to the point. For instance, don’t worry about including terms like ‘this is an image of’ or this is a picture of’ etc. because the code already tells the crawler that it is an image. However, when creating alt tags you can use longdesc=”” for more complex images that may require more text. 
• Target keywords but avoid keyword stuffing; alt text provides you with the opportunity to target keywords however as already discussed, the purpose of them is to describe images to those who may not be able to access them. Therefore, yes be sure to target keywords when appropriate but do not use this as an opportunity to “keyword stuff” (aka just use your keywords over and over in all images with no real context or relevance). You will be picked up on keyword stuffing which can have a negative impact on your organic results. 

Final Thoughts

To conclude, it is apparent that alt tags are extremely beneficial to all SEO campaigns however it is fundamental to remember that their primary purpose is for accessibility to those who need it. As marketing specialists, we must above all ensure that we are implementing alt texts to all images so that we follow legal guidelines, but use this opportunity to further target relevant keywords where appropriate.