Offline Maps

What do people mean when they talk about offline maps in conjunction with mobile navigation? How do they differ from online maps?
 
Online Maps
 
It makes it easier to appreciate offline maps when you understand what online maps are.  Online maps have been embedded in web pages for quite some time, but have become popular in phones in recent years with the rise of broadband internet for cell phones. 
 
Google Maps is one of the best known examples of online maps. Google Maps are embedded in thousands of web pages across the internet and are now available on software in your mobile phone. They can show both satellite pictures and street maps. 
 
Online maps are like streaming video. They depend on downloading data continuously from a server. 
 
They have a number of advantages for the urban user. No preplanning is necessary. If you can get location from either cell towers or a GPS chip, it can download jus tthe imagery for your area. You have the additional advantage of being able to look up information about nearby services such as the nearest pizza place.  
 
Despite these advantages, no true backcountry adventurer would rely on online maps. This is because they also have disadvantages:

• Maps are data intensive, using up bandwidth rather quickly when they are being continuously downloaded. 
• Internet access for using online maps in travelling is generally more expensive than internet access at your home or office, and may even cost up to a dollar per megabyte. 
• They become unavailable when you are away from a stable internet connection. 

Being away from the internet is like cutting off the water supply to offline maps. In many of the places where you would want to go hiking, kayaking, or exploring, you'd find that online maps simply won't work.   
 
Offline Maps
 
Offline maps, like the ones BackCountry Navigator uses, may be downloaded from an internet server or may come from other sources, including CDRoms. The key difference is that these maps will be stored on the file system or storage card of the device, so that they will still be available, and useful, when you find yourself outside the limits of cell coverage.
 
They can also be downloaded using your home internet connection, using Wifi or using desktop software, like BackCountry Navigator Desktop Edition, on your PC.  
 
Certainly there are challenges to offline maps as well. They require you to think in advance about the area that you will be covering, so you can prepare and download the appropriate map data. But planning is not necessarily a bad thing to do before you venture into the backcountry. Not only can you avoid getting lost, but you can plan for finding some of the places you wouldn't want to miss.   
 
Having maps that will be there when your coverage runs out is the key to finding your way in outdoor recreation.