:: Hassle-free Networking Without Interruption
NetworkManager is designed to be fully automatic and "Just Work" without intervention, but friendly desktop applications allow users to control the state of the network if they desire. NetworkManager keeps a list of all available network devices, and updates that list when you insert or remove new network cards, dock your laptop, etc. Using this list, NetworkManager determines the best device to use for the computer's network connection.
With this information in hand, the network connection is switched by NetworkManager to the best device, which is set up automatically via either DHCP or a static IP configuration. Wired LAN connections are preferred over wireless connections, since they offer the fastest speed and best reliability. So, when you come in to work in the morning and dock your laptop, your network connection automatically switches to the wired network connected to your dock. When you undock to go to a conference, NetworkManager switches the network connection to the wireless card, and automatically connects to a wireless Access Point that you've previously used. It even saves your WEP key so you don't have to enter it again.
If you haven't connected to any wireless network in the area before, a handy little networking menu on your desktop shows a list of available wireless networks, allowing you to choose a specific one. If that wireless network requires any type of encryption key (such as WEP or WPA), NetworkManager will prompt for that key, which you may enter in passphrase or in hexadecimal form. If you mistype the key, NetworkManager notices the mistake and prompts you again for the correct key.
Security conscious networking folk often set wireless networks not to broadcast their presence. In this case, NetworkManager allows you to specify a particular wireless network to connect to via the networking menu on your desktop or panel by typing the ESSID of the network directly. If the network is out of range or you've made a mistake typing it in, NetworkManager notices and helpfully informs you that the network is not available. In short, NetworkManager bugs you only when it needs to, to keep interruptions to a minimum.