This is WiFi serial transceiver module, based on ESP8266 SoC.

The SOC has Integrated TCP/IP protocol stack

Please note:This module is probably not for beginners, it's English documentation is sparse. Consider this product it a challenge/adventure. The price is great, but please do not buy this unless you are prepared to do some sleuthing to get it up and running. If you do manage to do something really cool with it let Anibit or Seeed know about it!

ESP8266 is a highly integrated chip designed for the needs of a new connected world. It offers a complete and self-contained Wi-Fi networking solution, allowing it to either host the application or to offload all Wi-Fi networking functions from another application processor.

ESP8266 has powerful on-board processing and storage capabilities that allow it to be integrated with the sensors and other application specific devices through its GPIOs with minimal development up-front and minimal loading during runtime. Its high degree of on-chip integration allows for minimal external circuitry, and the entire solution, including front-end module, is designed to occupy minimal PCB area.

Features

• SDIO 2.0, SPI, UART
• 32-pin QFN package
• Integrated RF switch, balun, 24dBm PA, DCXO, and PMU
• Integrated RISC processor, on-chip memory and external memory interfaces
• Integrated MAC/baseband processors
• Quality of Service management
• I2S interface for high fidelity audio applications
• On-chip low-dropout linear regulators for all internal supplies
• Proprietary spurious-free clock generation architecture
• Integrated WEP, TKIP, AES, and WAPI engines

Specifications

• 802.11 b/g/n
• Wi-Fi Direct (P2P), soft-AP
• Integrated TCP/IP protocol stack
• Integrated TR switch, balun, LNA, power amplifier and matching network
• Integrated PLLs, regulators, DCXO and power management units
• +19.5dBm output power in 802.11b mode
• Power down leakage current of <10uA
• Integrated low power 32-bit CPU could be used as application processor
• SDIO 1.1/2.0, SPI, UART
• STBC, 1×1 MIMO, 2×1 MIMO
• A-MPDU & A-MSDU aggregation & 0.4ms guard interval
• Wake up and transmit packets in < 2ms
• Standby power consumption of < 1.0mW (DTIM3)
• 3.3V NOT 5V tolerant!

Resources

• Espressif (Manufacturer of the SoC) ESP8266 List of downloads. <-- Always look here for the latest official software and firmware
• Very nice English writeup (and datasheet available) here
• Seeed Studio's ESP8266 wiki page (with Arduino examples)
• More ESP8266 Community forums