The information in these clauses is not essential. It tells us more about someone or something, but it does not help us to identify them or it.

Compare:

Punctuation

Non-defining relative clauses are always separated from the rest of the sentence by commas. The commas have a similar function to brackets:

Relative pronouns in non-defining clauses

Person

Thing

Place

Subject

who

which

Object

who/whom

which

where

Possessive

whose

Notes

This pattern is often used in spoken English, but in written or formal English you can also put the preposition before the pronoun: e.g. Stratford-on-Avon, about which many people have written is Shakespeare's birthplace.

Person Thing
all of + whom + which
any of + whom + which
(a) few of + whom + which
both of + whom + which
each of + whom + which
either of + whom + which
half of + whom + which
many of + whom + which
most of + whom + which
much of + whom + which
none of + whom + which
one of + whom + which
two of etc... + whom + which

Examples

Examples