Why Does YouTube place tracking cookies on your system?

[2048Megabytes]

I notice whenever I go to YouTube I get a lot of tracking cookies on my system. What data is Youtube hoping to harvest out of my machine but putting their crap software on my system?

 

[NyxCharon]

Information about what you watch so they know what ads to target you with.

 

[MyCattMaxx]

They have ads on YouTube?
Never seen one.