Qu'est-ce que Alt Text?
Définition Rapide
Le texte alternatif (alt text) est une description écrite d'une image utilisée sur les sites web, aidant les moteurs de recherche à comprendre les images et améliorant l'accessibilité.
Alt text serves two critical purposes: web accessibility and SEO. For visually impaired users who rely on screen readers, alt text provides a verbal description of images they cannot see. For search engines that cannot "see" images either, alt text explains what an image depicts, helping it appear in image search results.
Writing good alt text is both an art and a science. It should be descriptive but concise (typically 125 characters or less), include relevant keywords naturally (not stuffed), and accurately describe what the image shows. Decorative images that don't convey information can have empty alt attributes (alt="") so screen readers skip them.
Alt text is also what displays when an image fails to load, giving users context about what they're missing. This fallback function makes it important for user experience even beyond accessibility and SEO.
For e-commerce sites, product image alt text is especially valuable — it helps product images appear in Google Image Search, which drives significant shopping traffic. Descriptive, keyword-rich alt text on product photos can be a meaningful source of organic traffic.
Pourquoi c'est Important
Alt text is one of the easiest SEO wins most websites overlook. Google Images drives billions of searches daily, and proper alt text is the primary way to get your images found. Beyond SEO, alt text is a legal accessibility requirement in many jurisdictions — websites that don't provide it may violate ADA compliance standards.
For content-heavy sites, adding descriptive alt text to every image creates hundreds of additional ranking opportunities without creating new content.
Exemples Concrets
A food blog added descriptive alt text to 500 recipe photos and saw Google Images traffic increase by 40% within two months
An e-commerce store wrote unique alt text for 2,000 product images instead of using file names, leading to a 15% increase in organic product page visits
A real estate agency described each property photo with location, features, and room type, capturing searches like 'modern kitchen in Austin TX'
A nonprofit improved their website's WCAG compliance score from 62% to 94% simply by adding proper alt text to all images
Termes Associés
On-Page SEO
Le SEO on-page implique l'optimisation de pages web individuelles — contenu, code HTML et liens internes — pour mieux se positionner dans les moteurs de recherche.
Technical SEO
Le SEO technique désigne le processus d'optimisation de l'infrastructure de votre site pour que les moteurs de recherche puissent explorer, indexer et rendre vos pages de manière efficace.
SERP (Search Engine Results Page)
Une SERP est la page affichée par un moteur de recherche en réponse à une requête, contenant des résultats organiques, des annonces payantes, des extraits optimisés et d'autres types de contenus.
Meta Tags
Les balises meta sont des fragments de code HTML qui fournissent des informations sur une page web aux moteurs de recherche et aux utilisateurs, incluant le titre, la description et les mots-clés.
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