[Swarm-Support] what does '?' operator mean

[mohammed tayebi]

dear all
I find this instruction in the heatbug tutorial

<code>

 hereIsBetter = (type == cold) ? (heatHere < bestHeat)
              : (heatHere > bestHeat);

</code>

but I don't know what does '?' and ':' operator  means

thnk you for your helps