What is the participe passé and how to use it?

The past participle, called le participe passé in French, is very similar in French and English. It is important to recognise the French past participle’s structure. It usually ends in -é, -i, or -u, while its English equivalent usually ends in -ed or -en. The past participle has three main uses in French: Firstly, if it goes with an auxiliary verb (to have=avoir or to be=être), the past participle forms compound tenses such as the passé composé. (which is the past tense French speakers use the most and can be replaced in English with the preterit)e.g.: I played with the dog. —> J’ai joué avec le chien  Secondly, with être=to be, the past participle is used to form the French passive voice. The past participle can follow a verb in futur, present or past tense. This structure shows that the ongoing action described by the verb is passive. e.g.: The laundry is done every week by the maid. —> La lessive est faite toutes les semaines par la femme de ménage. Note: The word « by » often reveals a passive voice.  The third use is when the past participle stands alone, then it usually is an adjective.e.g.: Tired, I left the party early. —> Fatigué, j’ai quitté la fête tôt.Note: In the second and third use, the past participle needs to agree in gender and number with the word it modifies, following the normal rules of adjective agreement. When used to form the compound tenses, it may or may not need to agree, depending on certain factors. 
How to form the past participle of regular verbs? Drop the infinitive ending and add é, i or u respectively to -er verbs, -ir verbs or -re verbs. e.g.: to walk/walked —> marcher/marché      to finish/finished —> finir/fini     to defend/defended —> défendre/défendu Note: Most irregular French verbs have irregular past participles.