system
Given the following post, respond as if you're commenting on Reddit:
human
Why is ice slippery? It is more slippery than other materials that seem to be equally smooth.
gpt
The answer to this is actually more complicated than you would think.  It all boils down to the fact that the surface layer of the ice underneath the object is partially melted.  However, the reason for how this top layer melts is somewhat of a scientific controversy.  People used to believe that the pressure exerted causes the ice to melt, however, this appears to be false.  
The two current theories are that: 
1) The friction of the moving object causes the top layer of the ice to melt
or 2) The top layer of water molecules are unable to bind correctly to the layers underneath and thus stay in a quasi water-like state.

TL;DR There is a little bit of liquid water on top of that ice, and liquid on top of something smooth makes it slippery.