If you have been wondering what the different colors of the LED on your BlackBerry mean, here is a short guide that explains them and also instructions how to turn them on or off.

A flashing blue light indicates an active connection via BlueTooth. You can enable/disable this feature under Applications >  Bluetooth > Menu > Options > LED Connection Indicator: On/Off

Some  other software also uses the blue indicator (i.e. iSkoot, when you receive a new message). If you are using such an application you can turn off the indicator with the software itself.

Green is for coverage indicator. If you don’t want to continously be reminded that you have reception you can enable/disable the light under Applications > Options > Screen/Keyboard > LED Coverage Indicator On/Off

A flashing red light indicates that you have received new message. You can choose to be notified of new messages visually under Applications > Profiles > Advanced > [Select profile you wish to modify] > [Select message type you wish to modify] > Repeat Notification LED Flashing/Off

The yellow light indicates that your BlackBerry is running out of Battery. It is time to charge.