Definition of the ALT tag 

Through our SEO Agency Optimize 360

The web is a medium largely based on images and their use, whether for communication, marketing or simply to make a site more attractive.

However, it is also essential to think about setting up anchors html to optimise the presentation and referencing of the pages containing them.

One of the most important markers in this context is the ALT tag. Let's find out from our SEO Agency what it is and what it is used for, so that images are referenced in Google.


ALT tag

What is the ALT tag?

The ALT tag (from its English name, "alternative text") is a HTML command to associate a text alternative tag to a visual element, usually an image. This tag is written in the form :

<img src="image.jpg" alt="Description of the image" />


  • img is the tag indicating that it is a visual element,
  • src is the attribute specifying the location of the image file,
  • alt is the attribute used to add an alternative text describing the image.

Why use the ALT tag?

Improving content accessibility

The ALT tag enables visually impaired people or those with image reading difficulties, such as screen reader users, to understand the meaning of a visual element without being able to see it directly. When the image is not available or cannot be displayed correctly, the browser displays the alternative text instead.

Optimising referencing

As well as making your web pages more accessible, the ALT tag is also a key factor in optimising your site's SEO. Search engines like Google analyse alternative texts to determine the subject and relevance of an image in relation to the content of the page.

So using relevant alternative texts can help to improve the position of your pages in search engine results and therefore boost their visibility.

How do you write a good alt attribute?

Be concise and precise

An alt attribute should be short and concise enough to be easily understood, but detailed enough to give a clear idea of what the image represents. Ideally, it should describe in a few words, for example :

<img src="voiture-ancienne.jpg" alt="XYZ vintage car" />

Avoid unnecessary keywords

There's no point in overloading your ALT attribute with keywords that have nothing to do with the image. Search engines like Google can detect this type of practice and penalise your site in their results.

Mention the purpose of the image if necessary

If the image fulfils a specific function (link, button, icon, etc.), it is important to mention this object in the alternative text:

<img src="logo-site-web.png" alt="Logo du website" />

Avoiding redundancy with neighbouring content

When the text content around the image already explicitly describes the image, it is not necessarily useful to repeat this information in the alt attribute. In this case, you can choose to leave the alt attribute empty:

<img src="equipe.jpg" alt="" />
<figcaption>The entire team</figcaption>

Best practice for using the ALT tag

  • Use the ALT tag systematically : Each image inserted into your content must be accompanied by an alt attribute, including decorative elements. This makes your pages more accessible and easier to reference.

  • Regularly test your site using specific tools: There are a number of online tools available for checking whether all the images on your site have an alt attribute. Remember to carry out these checks regularly, particularly after you upload new content.

  • A relevant description: The quality of the alternative text is essential for a good user experience and optimal referencing. It must be clear, precise and correctly describe the content of the image.

In conclusion, the ALT tag is an essential element of a web strategy efficient.

It helps to optimise website accessibility and referencing, while making visual content easier to understand for all users.">Systematic and appropriate use "This HTML tag is therefore essential to ensure good positioning on search engines and a better experience for your visitors.

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