Based on the ESP8266 Wi-Fi module and with a form factor compatible with Arduino Uno, this board allows you to create applications that require Wi-Fi connectivity and the easy to use of Arduino. The ESP8266 is a small Wi-Fi transceiver module compatible with the 802.11 b / g / na 2.4 GHz standard and has integrated TCP / IP stack, output power of 19.5 dBm, data interface (UART / HSPI / I2C / I2S / Ir Remote Control GPIO / PWM) and antenna on PCB. Programmable via Arduino IDE, the board has 11 digital I / Os with interrupt / PWM / I2C / one-wire (except D0), 1 analogue input (max 3.3 volt), micro USB connector, reset button, power input from 9 to 24 volts, 5 volt output 1 A.

• Model: ESP8266-12F
• Standard Wireless: 802.11 b/g/n
• Frequency range: 2,4 GHz - 2,5 GHz (2400M-2483.5M)
• Wi-Fi mode: Station / SoftAP / SoftAP+station
• Stack: TCP/IP on board
• Output power: 19.5dBm, 802.11b mode
• Data interface: UART / HSPI / I2C / I2S / Ir Remote Control GPIO / PWM
• Security mode: WPA / WPA2
• Criptography: WEP / TKIP / AES
• Supports AT commands: yes
• Power supply: 3 Vdc to 3,6 Vdc (recommended 3,3 Vdc)
• Consumption: average 80 mA - standby mode < 1 mW
• Working temperature: -40°C to +125°C
• Certification: FCC / CE / TELEC
• Dimensions (mm): 24x16x3
• Weight: 3 grams

• https://github.com/esp8266/esp8266-wiki/wiki