The English past perfect is used to indicate that an action occurred in the past before another action in the past. It is conjugated with had plus the past participle.
The simple form emphasises the fact of the action and may be used alongside the simple past, conditional, or past conditional.
They had won the race before they celebrated.
When the show had finished, the audience left in silence.
If you had lived in England, you would speak better English.
I would have talked to you if I had seen you.
Like other English tenses, the past perfect also has a progressive form.