Main features of ESP8266 are:
- Integrated low-power 32-bit MCU
- 802.11 b/g/n protocol
- UART/SPI/I2C/GPIO/ADC/PWM
- Infrastructure BSS Station mode / P2P mode / softAP mode support
- Integrated TCP/IP protocol stack
- WPA/WPA2 PSK, and WPS driver
- built-in AT Command firmware
- Integrated PLL, regulators and power-management units
- +19.5dBm output power in 802.11b mode
- Antenna diversity and selection (software managed hardware)
- SDIO 2.0, SPI, UART
- Maximum frequency is 80MHz
- 64k bytes of instruction RAM
- 96k bytes of data RAM
- 64k bytes of boot RAM
- RISC architecture
