When you are listening to music on the iPhone, you can use the squeeze button on the headset cord to control your music playback.

Squeezing the button once when a song is playing will pause the song, squeezing again will start the song playing again.

If you double-squeeze the button while a song is playing, the song will be skipped and it will start playing the next song in the album or playlist.

If you squeeze the button once to pause a song, and you then double-squeeze, this will restart playing the album or playlist from the first song.