What Does a Ported Sub Box Mean In The Car Audio World?

I am new to the bass scene. What are ported subwoofer boxes? Why do they have a big plastic hole on the side, does it cool down the speaker?

Ok, a ported subwoofer box is constructed from MDF. The ported hole is a plastic vent that is tuned to a specific frequency. The job of the ported box is to play louder around a certain frequency region that its tuned to specifically. Taking the length and diameter into consideration of the plastic piping. This is why they tend to sound more boomy and deeper making them sound good for bass heavy rap music over a sealed enclosure anyday. They are more harder to get right and require much more advance calculations, its not as simple as building a square shape.