Making content appear in the user's local language. There is a separate tag [translation].
Localization is a process whereby translators will translate strings to different languages to make the content of a site appear in the local language of the visitor, or the preferred language that the user has set to make the site appear in.
Localization will allow the site to be shown in the language that the visitor is more comfortable with, instead of serving content that the visitor might not understand very well.
