The ESP8266 WiFi module is an easy to use and popular module for the development of Internet of Things - IoT and WiFi related projects and applications.This low cost module greatly simplifies building IoT products. The ESP8266 Module is available in many variants. This ESP-01 Variant is the most popular and easy to interface module.
This module is suitable for multiple projects both easy and complex form turning an LED on and off, switching a device on and off, uploading data to the internet and cloud, etc. It can also communicate with multiple sensors and devices through its input pins with minimal external components.
The ESP8266 can be programmed through Arduino IDE just like an Arduino after a simple firmware change. Alternativly you may also use the module for communication over WiFi and offload all the processing load to an external microcontroller. It can communicate with an external microcontroller through a simple serial UART interface. It comes with an onboard PCB Antenna and requires no external antenna.
ESp8266 has different modes of operations for multiple applications. It can communicate over WiFi in two different modes. It can connect to an existing wireless hot spot, or access point, similar to the way you connect your phone or computer to the Internet. This is called “station” mode. In station mode the ESP8266 board can reach out to the internet and may also communicate with other devices connected to the same network, including other ESP8266 modules.
ESP8266 module can operate as a soft access point (Soft AP), broadcast its own WiFi Network and support up to 5 Wi-Fi client devices, or stations, connected to it.