The relative clause identifies the person we mean.

A defining relative clause has no commas.

The non-defining relative clause adds extra information.

The noun clause explains what she decided.

The participle clause makes the sentence shorter.

I met the artist whose work won the prize.

We do not know whether the train is delayed.

The neighborhood that we visited was very quiet.

The exhibition, which runs until Friday, is free.

The volunteer who greeted us spoke three languages.

I explained why I submitted the application late.

The recommendation that you gave me was useful.

Having received a complaint, the manager called the customer.

I understand the decision that the group made.

The guide gave an explanation that everyone understood.