I have recently published a new version of my website, a photographer's portfolio site. The site is bi-lingual, English and German.

Compared to the previous version, I have tidied up the code, stripped out obsolete tags, improved (hopefully) titles and descriptions and distributed the content over more pages - and visitor numbers have already increased considerably.

Does anybody have a view whether using the content-language tag serves any useful purpose? Surely, at least the major search engines determine the content language automatically?