La balise Hreflang :
Quand dois-je l’utiliser : (Source)
La langue du contenu principal ne change pas et seul le modèle de la page est traduit, comme les éléments de navigation et le pied de page. C'est souvent le cas sur les pages dont le contenu est généré par l'utilisateur, comme un forum.
Votre contenu reste globalement fixe dans une langue donnée, à l'exception de quelques variantes régionales. Par exemple, un contenu en français peut cibler les internautes de Belgique, de France et de Suisse.
Le contenu du site est traduit dans son intégralité dans plusieurs langues. Chaque page est disponible en allemand et en français, par exemple.
Exemple concret :
Je suis Apple, j’ai un site international :
<link rel="canonical" href="https://www.apple.com/fr/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="fr-fr" href="https://www.apple.com/fr/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="de-de" href="https://www.apple.com/de/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="fr-ca" href="https://www.apple.com/xf/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-au" href="https://www.apple.com/au/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="tr-tr" href="https://www.apple.com/tr/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="pl-pl" href="https://www.apple.com/pl/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="ru-ru" href="https://www.apple.com/ru/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-gb" href="https://www.apple.com/uk/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="it-it" href="https://www.apple.com/it/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="ja-jp" href="https://www.apple.com/jp/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-ca" href="https://www.apple.com/ca/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="es-es" href="https://www.apple.com/es/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="sv-se" href="https://www.apple.com/se/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-ae" href="https://www.apple.com/ae/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-us" href="https://www.apple.com/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="fr-ch" href="https://www.apple.com/ch-fr/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="zh-hans-cn" href="https://www.apple.com/cn/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="fi-fi" href="https://www.apple.com/fi/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-ie" href="https://www.apple.com/ie/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="da-dk" href="https://www.apple.com/dk/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-my" href="https://www.apple.com/my/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="ko-kr" href="https://www.apple.com/kr/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="zh-hant-tw" href="https://www.apple.com/tw/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="de-at" href="https://www.apple.com/at/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-th" href="https://www.apple.com/th-en/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="es-mx" href="https://www.apple.com/mx/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="hu-hu" href="https://www.apple.com/hu/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-nz" href="https://www.apple.com/nz/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="pt-br" href="https://www.apple.com/br/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="nl-be" href="https://www.apple.com/be-nl/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="no-no" href="https://www.apple.com/no/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-ph" href="https://www.apple.com/ph/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="th-th" href="https://www.apple.com/th/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="cs-cz" href="https://www.apple.com/cz/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="fr-be" href="https://www.apple.com/be-fr/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="fr-lu" href="https://www.apple.com/lu/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="pt-pt" href="https://www.apple.com/pt/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="nl-nl" href="https://www.apple.com/nl/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="zh-hant-hk" href="https://www.apple.com/hk-zh/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-sg" href="https://www.apple.com/sg/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="de-ch" href="https://www.apple.com/ch-de/shop/buy-iphone/iphone-11" />
<link rel="alternate" hreflang="en-hk" href="https://www.apple.com/hk/shop/buy-iphone/iphone-11" />