ESP8266 is an inexpensive serial-to-wifi transceiver chip that can be used to connect any microcontroller with a serial port to a WiFi network. Because of its simplicity and low cost, it is getting popular among hobbyists for implementing it in Internet of Things (IoT) applications. ESP-01 module provides access to the power supply and I/O pins of ESP8266 through a 2x4 male header. But the pin arrangements are not user friendly.
This “ESP8266 ESP-01 Wifi Mini Development Board” has a 6 Pins L-Shape Male header for Programming. Other 4 Pins are Yellow Male header for 3.3V, GND, GPIO2 and GPIO0. There’s also Flash and Reset Switch.