As a personal pronoun (both subject and object),onecan be used to refer to ‘people in general’. We often useonein making generalisations, especially in more formal styles. However, ifoneis used too much, it can make the speakersound too formal.Onetakes a third person singular verb:
Onenever knows, doesone?
Oneshould not use mobile phones when driving.
Holidays are supposed to allowoneto forget about work.
Youandtheyare also used in a similar way. However,oneandyouinclude the speaker in the generalisation:
[a durian is a kind of fruit]
Doesoneeat durian in Malaysia?(includes the speaker, who is there or has an interest in going there; more formal)
Doyoueat durian in Malaysia?(less formal)
Dotheyeat durian in Malaysia?(refers to others)
One’sis a possessive determiner:
One’shealth is much more important than having lots of money.