The Steadicam was invented

by Garrett Brown and it's best

to quote (a part of) his own

list of why one would use

Steadicam:

1. •moving camera shots in tight quarters
   

2. •shots over rough ground
   

3. •where one needs to continue beyond where track
   cannot be accommodated
   

4. •where any other technique for moving the camera
   

            would be impractical externally (ie. a bridge or dock)

1. •where one needs to isolate the camera from
   

            the movement of a vehicle

1. •where one wishes to simulate vehicle motion
   

            within a set that doesn't move

1. •for human or non-human points of view
   

2. •for quick static shots or unpredictable events,
   

            where time is a factor

The list goes on. But it's easy to say that Steadicam makes the impossible possible.