The ESP8266-12E can add Wifi capability to any Arduino project.  This is for advanced users only.

The ESP series of controllers is made by a company called Espressif.

FEATURES:

• Processor: L106 32-bit RISC microprocessor core based on the Tensilica Xtensa Diamond Standard 106Micro running at 80 MHz
• Memory:
• 32 KiB instruction RAM
• 32 KiB instruction cache RAM
• 80 KiB user-data RAM
• 16 KiB ETS system-data RAM
• External QSPI flash: up to 16 MiB is supported (512 KiB to 4 MiB typically included)
• IEEE 802.11 b/g/n Wi-Fi
• Integrated TR switch, balun, LNA, power amplifier and matching network
• WEP or WPA/WPA2 authentication, or open networks
• 16 GPIO pins
• SPI
• I²C (software implementation)[6]
• I²S interfaces with DMA (sharing pins with GPIO)
• UART on dedicated pins, plus a transmit-only UART can be enabled on GPIO2
• 10-bit ADC (successive approximation ADC)