ARP broadcast

hi

Do you know what is the main feature for ARP broadcast?

i have 2 questions as below, hope you can answer my questions.

1.) usually what device will do ARP broadcast? Router? and can let me know why ?

2.) ARP funstion is turn the network layer to data link layer ? and then the data can deliver to physical layer hardware?

3.) when will the reverse address resolution protocol (RARP ) working, can give me a example?

and i correct ? please i need you to correct me. appreciate your answer.