The Nintendo Wii gaming system lights up in a variety of ways and colors, and each light notifies you of a specific occurrence. Blue LED lights, found on both the console and the Wii remote, either illuminate solidly or flash, depending on the notification they are transmitting.
WiiConnect24, the Wii's messaging system, is one of the functions that utilizes the blue light on the console's disc slot. When active, WiiConnect24 notifies users of new messages (either message board messages or messages from Nintendo) by causing the blue light to flash on and off. Checking your WiiConnect24 messages causes the disc slot to stop flashing blue. You can change the indicator's brightness (or turn it off) by selecting "Bright," "Dim" or "Off" from the "Slot Illumination" menu in WiiConnect24's settings.
The game disc slot on the front of your Wii console occasionally flashes blue to indicate that the system is powered on. This happens when a disc is inserted, when the system is powered on by the Wii remote or when it is powered on by the console's power button. The blue power indicator flash is very rapid and is only triggered by one of these actions.
There is a row of four blue lights on the bottom of each Wii remote. Like the disc slot light, the remote's lights serve as notifiers to the user. Each time a Wii remote is activated, the blue LED lights blink multiple times to indicate the remote's remaining battery power. All four lights illuminating indicates full (or nearly full) battery strength. Afterwards, a single blue LED remains lit. This light's placement indicates which player the remote is for. For example, if the second blue light is lit, that would be player two's remote.
Other LED Indicators
The blue LED lights on your console and Wii remote also flash when you sync the two. Syncing is done with a new remote by pressing the sync button under the SD card slot cover on the console and the sync button under the battery cover on the remote. There are other LEDs that illuminate on your console as well. For example, the power LED on the front of your Wii, in the top-left corner, lights green when the Wii is powered on, red when it's off and orange when it's in standby mode.