We defined network applications, as opposed to stand-alone applications, as those in which either the data, programs, or both are stored on the network.
All network applications store data on a server, but some also store copies of the data on the client. That enables a user to work when off line -- perhaps when traveling -- and automatically synchronize the data on the two machines when the client re-connects to the network.
This short video illustrates offline editing while using Zoho's Writer word processing service, and you can read more about it here.
Note that it uses Google Gears, an open source program that must be installed on the client computer.
Google wrote and supports Gears as an open source project -- what is their reason for doing so? Why is Gears strategic for Google?