Yeah, that’s common in India. Everyone is expected to learn the local language, English, and (in most places) Hindi. So people from different states communicate with each other in English. Similarly, the Union (=Federal) government uses English and Hindi while each state and territory can decide its own administrative language(s).

The Netherlands, despite being tiny, has 4 official languages (Dutch, Frisian, Dutch Low-Saxon, and Limburgs). We also used to have a different dialect for each city, so you could hear something else every 10 minutes driving! But only a handfull of dialects are left nowadays.

Everyone in the whole country speaks Dutch (al be it with slightly different accents), so that’s one common everyone has. In the areas with local languages it depends. In Frysia, Frysian is spoken a lot and used in by the local goverment as well. Dutch Low Saxon and Limburgs are in an kinda odd situation. They where dying and only got officially recognised not that long ago, but thr native speakers left are proud and like to preserve. However, it has a weird status where the local goverment isn’t allowed to use it despite being recognised. While it’s spoken in many people in more rural areas, there are also people from those areas who can’t (especially in cities) or who mix the local language and Dutch. What is spoken together depends on whatever both people speak: if it’s the local language they use that, if it’s half/half they use that, else they use Dutch. People who mix or speak a local language might end up teaching their partner some mixed speech too.

Then we also have a lot foreigners who don’t speak Dutch, especially in the bigger cities (like Amsterdam, Rotterdam, Utrecht, Den Haag) and villages around them. About half our population is foreign. Due to that, it’s not uncommon for people to switch to use exclusively English despite it not being an official language. However, older Dutch natives don’t always speak English very well, and the more rural the less common English becomes.

We’re quite international oriented here. On top of previous languages listed, almost all Dutch people will learn at least 2 more foreign languages in high school; often French and German. However, those are rarely used unless we need it to talk to a native speaker. Similarily, we learn foreign languages if we’re interested or it’s useful to us. I for example have had some formal education in Japanese and Mandarin during my time in university, and want to learn more Cantonese and maybe Vietnamese as well.

What parents speak to their kids also depends on the combination of languages the parrents speak.

An example of how that works in reality (our first kid is due to be born late November):

I’m Dutch from the area we speak Dutch Low-Saxon, and natively I speak the local language and Dutch (outside of learning both, my dad’s side of the family speaks the local language while my mom’s side speaks Dutch). My partner is Chinese-Vietnamese (his grandma left China for Vietnam) with a Dutch passpoort (1st generation). He speaks some Dutch but it’s limited. We usually speak English, but try to use Dutch as well so he can practice. However, I also use Dutch Low-Saxon words with him (for example “skotteldoekie” instead of the Dutch “vaatddoek”, “siepeltie” instead of “ui”, etc etc).

My partner speaks Vietnamese and Cantonese originally, but while he mixes them with his family he rarely mixes it with Dutch or English. We do use some words, mainly when they’re more specific than their common translation or have none at all. Think a “chi gold” (chi is a measurement unit; 1 chi is roughly 3,75mg) or “lap cheong” (a type of chinese sausage, often translated to simply “Chinese sausage”).

We plan to both speak our local language (Dutch Low-Saxon and Cantonese) to our kid. Since Dutch is used all around they’ll hear that from us too when speaking indirectly, and since we speak English regularily that will be heard as well.

I’m always amazed at how well basically every Dutch person I ever met spoke German. The languages are pretty similar but my Dutch is still terrible.

Not my parents, but as a parent my wife and I have different native languages. I speak to my son in English, the only language I know. My wife talks to him in Indonesian unless it’s a conversation involving me then it’s English.

My son will answer her in English even though he can speak and understand Indonesian. Although his Indonesian accent is becoming more influenced by English as he gets older, probably due to the lack of using the language. Calls with his grandmother help as she doesn’t speak English but she’s partially deaf which doesn’t help.

I know a couple who speak French and Spanish, and English is the majority language here. They speak and reply to each other in their own language. It’s amazing and I love it.

My dad’s side of the family is all native French and default to speaking that. I grew up with my English mum though so I didn’t learn it. It makes family gatherings on that side a bit awkward since I’ll just be sitting there trying to parse what everyone is talking about

Edit: this is in Canada

My mother is Norwegian and my father is German. I grew up in Germany. When we were young my mother would speak Norwegian with us. But she stopped when we had friends over because it seemed rude to her. Eventually she stopped entirely.

I wish I had kept it up. Although apparently it wouldn’t have done us much good in most of Norway. When my father had some Norwegian business partners over he wanted to impress them with his Norwegian. They didn’t understand a word because he learned it from my mother who apparently has a very thick accent.

Both my parents can speak German and English I spoke German with my Dad and English with my mum, when we were young my siblings went to German schools so we spoke more German at home. We then went to English schools so I spoke more English with my siblings, my Dad would always speak German to us though.