Dream-Sharing is the practice of manufacturing a dream and bringing one or more people into that new dream world. While dream sharing, one person creates and controls the world (the architect), while another (the subject) populates it with both people and information. Dream-sharing was first utilized by the military to provide a realistic training method for soldiers. It can also be used to commit Extraction by stealing information and Inception by planting information in the form of an idea into the mind of the subject. Miles brought Dom and the others into dream-sharing to prove to them that their creativity was limitless.
One method used to awaken from a dream is called the "kick", which is the sensation of falling, or a sharp jolt. This startles the dreamer out of their sleep. However, in order to wake up when dreaming within dreams, a kick is required in each layer of dream, and all of them must be executed one after another close to same time (which is made difficult due to time-dilation caused by dreaming in multiple layers) to have enough impact to arouse the dreamer from their sleep. Music is a way to coordinate the kicks. When dreaming on only one level, a timer mechanism on the PASIV Device can be used to wake up dreamers.
To initiate dream-sharing, special medication is needed. Somnacin is one of the drugs used for this purpose.