How long to play a track before it is countedas listened to?

[SpeedyMan]

This is a technical question about how Spotify counts a track as having been listened to.

I read that in order for Spotify to pay an artists for 1 streaming of track, it has to play for at least 30 seconds...

But how long do I have to listen to a track before Spotify counts it as "played" and uses it to determine recommendations like for my Daily Mixes, for example? 30 seconds? 50% of the track? The entire track? Just the last few seconds of the track?

Thanks for any information