Jakob Nielsen suggests: The advised option is to make use of flags that match the geographical area of the service and its major desired audience. A tourist site in Continental Europe would use a British flag Flag of the United Kingdom for English unless it was mainly targeted at American tourists. Whereas a tourist site in the Americas would use a U.S. flag unless it were mostly targeted at Europeans.
I have seen the English Flag of the Kingdom of England utilized when, however, would recommend this apparently neutral choice since few people outside the U.K. know the local flags for England, Scotland, etc
In summary, it is suitable to use nation flags as long as they are used along with the name of the country and are utilized as a visual help only. It is commonly appropriate to incorporate two countries together to assist the user experience. For instance, a UK site might let users select US/Canada rather than offering various pages for each area.
So far, we have been assuming that readers in a specific nation will always want to read your site in the native language of that country. Clearly this isnt constantly the case, and this raises several problems.
Of all when your users pick their location it is crucial to identify that from the language they want to make use. A user in Spain might desire to understand about how your business runs in their local market but want to read the site in French. Do they click the French flag or the Spanish flag?
In his column on International Usability Nielsen suggests:
To select in between a little number of languages, I recommend noting the name of each language as a word, using each languages name for itself.