ESP-12 (ESP8266 ) is an ultra-low power UART-WiFi module. It has excellent dimensions and ULP technology compared to other similar modules. The module is special design for mobile devices and Internet of Things . Once firmware is upgraded to the appropriate version, a compatible Android device can run the IOT.APK to do the following:control the PWM, I/O pin, or Serial communication. For example,you can use this module transmit date with it serial port.It is easy to communication with other device.
When searching for this over a WiFi network, the device name is "AI-THINKER" and the password is "ai-thinker". In the photos you can see an Android phone running a control app, the APK download is available from here. 

Features

• Metal casing

• support wireless 802.11 b/g/n standard

• support the STA/AP/STA + AP three work modes

• support rich Socket the AT command

• support UART/GPIO data communication interface

• support Smart Link intelligent networking

• support the STA/AP/STA + AP three work modes

• built-in 32-bit MCU and can be applied as processor

• low power consumption, suitable for battery-powered applications

• Single 3.3 V power supply

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• Wiki