There are three main options for GPS. 1. Use Wireless Networks 2. Use GPS Satellites 3. Enable Assisted GPS What should you have on and when should you have it on? What uses the MOST battery...the LEAST battery? I know Option 2 is required when using the navigation....really option 2 is the most commonly known form of GPS. The other two get a little fuzzy in what they do and when and if we should even turn them on.