http://learnenglish.britishcouncil.org/en/grammar-reference/relative-clauses-non-defining-relative-clauses

Relative clauses - non-defining relative clauses
Relative clauses add extra information to a sentence by defining a noun. They are usually divided into two types – defining relative clauses and non-defining relative clauses.

Non-defining relative clauses


Look at this sentence.

  • My grandfather, who is 87, goes swimming every day.


‘who is 87’ is a non-defining relative clause. It adds extra information to the sentence. If we take the clause out of the sentence, the sentence still has the same meaning.
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What does “If we take the clause out of the sentence” in the above context mean?


Do the following sentences have a difference?

1. I went to visit my uncle , who lives in Thailand.
2. I went to visit my uncle who lives in Thailand.

Thanks.