Changes

If you are on an open wireless network (i.e it does not use any form of encryption) then it is possible that Ubuntu will automatically locate the network and connect to it. This is because Ubuntu is configured by default with roaming mode enabled. In roaming mode the networking system searches the airwaves for wireless networks it can connect to. If it finds either an open network, or one for which it has the encryption key it will automatically connect. A status indicator in the top right hand corner of the desktop indicates whether or not a network connection is active. The indicator icon shows two computer monitors. If the icon shows a red warning triangle with a white exclamation mark (as below) then there is currently no active connection.

Clicking with the left-hand mouse button on the network connection status icon will cause a drop down menu to appear: