Minimap

The Mini Map is a HUD element that represents the entire map on a smaller scale. It displays in real time the location and status of structures (green for Radiant and red for Dire). It also shows the current location of all heroes within sight range, as well as creeps and Roshan.

Pinging
Holding down the Alt key and clicking on the Mini Map will "ping" all allied players. A colored circle with an exclamation point will appear at the location pinged, both on the Mini Map and on the main map. Also, a noise will sound. The pitch of the noise and the color of the circle correspond to the color of the player's name. If the ping is centered on an allied tower, then a small shield will be displayed there on the Mini Map. If the ping is centered on an opposing tower, a small sword will be displayed there.

Drawing
Holding down both the Ctrl key and the left mouse button while moving your cursor over the Mini Map will draw lines on the Mini Map. These lines can be seen by all allied players, and their color corresponds to the color of your name.