What is Diglossia?
Diglossia is when a language community uses two varieties side by side: a formal 'high' variety for writing, media and school, and a spoken 'low' variety for daily life. Arabic is the classic case — Modern Standard Arabic in the news, Egyptian or Levantine dialect at the dinner table.
Arabic learners meet diglossia head-on: study only Modern Standard Arabic and you'll read newspapers but sound like one at parties; study only dialect and you can't read. Swiss German (spoken) versus standard German (written) is another famous pair, as is Tamil's formal/spoken split.
The practical answer most teachers now give: pick the spoken variety of the region you care about, learn the high variety in parallel or later, and accept that natives themselves navigate the split daily — it's not a learner-only problem.
What it means for your speaking
Diglossia is precisely why speaking practice must target the SPOKEN variety — hours of formal-register drilling can leave you unable to order a coffee naturally. Practise the language people actually answer back in.
Practise out loud — 30 seconds a day →