The ESP8266 is a low-cost Wi-Fi microchip with full TCP/IP stack and microcontroller. The ESP8266 WiFi Module is a self contained SOC with integrated TCP/IP protocol stack that can give any microcontroller access to your WiFi network. The ESP8266 is capable of either hosting an application or offloading all Wi-Fi networking functions from another application processor. The ESP8266 can be controlled from your local Wi-Fi network or from the internet (after port forwarding). The ESP-01 module has GPIO pins that can be programmed to turn ON/OFF LED or a relay ON/OFF through the internet. The module can be programmed using an Arduino/USB-to-TTL converter through the serial pins (RX, TX).

Features:
•    802.11 b/g/n protocol
•    Wi-Fi Direct (P2P), soft-AP
•    Integrated TCP/IP protocol stack
•    Integrated TR switch, balun, LNA, power amplifier and matching network
•    Integrated PLL, regulators, 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 2.0, SPI, UART
•    STBC, 1×1 MIMO, 2×1 MIMO
•    A-MPDU & A-MSDU aggregation & s guard interval0.4  
•    Wake up and transmit packets in < 2ms  
•    Standby power consumption of < 1.0mW (DTIM3)