Definition
With the alt tag, or more precisely the alt attribute, you can indicate to Google an image's content. The objective is to target a position on Google Images, and more widely contribute to the semantic understanding of a page.
It corresponds to a part of a page's html code, but don't panic, you don't need to know how to code >> all CMS like WordPress, Magento, Shopify, etc. indicate an alt field to complete when importing images.
Alt attribute of an image: Why is it important in SEO?
Optimizing its alt tag is to optimize its SEO, the keywords contained in the alt tag are taken into account for the page’s position on search engines: this attribute helps Google contextualize your content.
Universal search is increasingly important. Referencing your images in search engines becomes essential to be visible, and this can generate traffic to your site via Google Images for example.
The alt attribute is read orally by the screen reader for visually impaired people.
It will be the content displayed if your site is slowed down by any problem (server, slowness...), so it is supposed to tell the user what should be found instead of this image.
How to optimize your images for SEO?
Define the alt tag of the image by describing your images with a simple expression and keywords on which you want them to rank in search engines
And concretely then: Choose between 5 to 6 keywords that will describe what your image represents. The idea is to present its content and its function.
Example: for the image below, "group cooking classes".
It's hard to talk about image optimization without talking about :
Image size
Make sure you don't use images that are too heavy to avoid slowing down the loading time. In principle, an image should not exceed 100 Kb. When a page takes too much time to load, search engines spend too much time (to the detriment of your other content), and moreover you have a great chance that the user leaves your web page. You have the possibility to compress your images with plugins like wp smush for Wordpress, or Optimzilla to easily compress images.
Title attribute
The TITLE attribute is the text that appears when you put the mouse on the image. This text is not taken into account for ranking in Google and is therefore not very important in SEO. But it may be interesting for your users to fill it!
Caption
Ideally all your images have a small caption that describes the image with terms a little different from those used for the alt attribute. Again, this will help Google contextualize your image.
The file name
It is composed of keywords related to the image. Attention: no "_" , no capital letters or accented characters.
How to set up the alt attribute of an image ?
The alt attribute is a part of the HTML code of a page that is simple to fill in. We don't necessarily need to know how to code, the CMS such as WordPress indicate an alt field to fill in for each of your images on your site.
So if we take the example of WordPress, the alt tag of your image will be under the name "alternative text". If this field is empty, it is important to fill it with a title corresponding to the content of the image.
Optimizing your images requires some work to do it properly. Nevertheless this investment will be beneficial for your positions and organic referencing. Do not neglect this important textual element, because it is part of good SEO practices that will increase your chances of being on the first page of search engines!
Images and alt attributes: mistakes to avoid
Do not confuse alt and title attributes
A header in image (header), often on sites have the possibility to have a header in image or even a logo. Avoid it! The header is one of the most important areas of your site where you need to integrate your main keywords to optimize your SEO.