The Future Light Cone of an Event

Yihikah says, could you please tell about future light cone of an event? Why is it shaped like a cone? How does it does it divide space time into past and future light cone? Okay. When you talk about space time, it's a four dimensional fabric. We know that space we see it, we perceive it in three dimensions,. And then time is taken as a fourth, fourth dimension in general relativity. These together make up the four dimensional fabric of space time. So, when you want to create a light cone, like you're saying, you have to treat space space itself as a two-dimensional sheet.