This is the pin compatible upgrded version of the ESP-01 chip.
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.
This is a splittable 40 pin jumper wire, it is super flexible, can be transformed from 1-40 pin jumper wire. With some of these, you will no need to worry about the jumper wires you got before do not fit your project, just split it and go.