Our PHP framework supports multi-language content. There are two groups of multi-language content: first, static labels, messages, paragraphs, etc; and second, are database content (e.g. products, posts, etc).
Static Content
With a built-in function t with a dictionary.csv file behind, end user (also including search engines and crawlers) are able to view web pages rendered in their preferred langauge.
Function t('...') will iterate over the dictionary and return equivalent phrase in the desired language-region passed in the URI.
Dynamic Content
The web server must follow some rules in database design and/or its returning schema, so the front-end will parse the results as expected.