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.
Specifications:
Serial/UART baud rate: 115200 bps
Input power: 3.3V
I/O voltage tolerance: 3.6V Max
Flash Memory Size: 1MB (8Mbit)
WiFi security modes: WPA, WPA2
Package Including
5 * ESP8266 Wifi Transceiver Module
Support 3 modes: AP, STA, AP + STA
Model:Esp-01 Compatible with Arduino
Link to view the technical details, https://nurdspace.nl/ESP8266
Introduction: https://github.com/sleemanj/ESP8266_Simple
WiFi security modes: WPA, WPA2