The 4-Channel Relay Module (Red Board) is a widely used switching module that allows low-voltage microcontrollers like Arduino to control high-voltage AC/DC devices safely.

This module includes four independent relay channels, enabling control of multiple devices such as lights, fans, motors, and appliances. It is available in both 5V and 12V variants, depending on the relay coil voltage.

Each channel features an optocoupler for electrical isolation, improving safety and reliability. The module supports both high-level and low-level triggering (depending on configuration), making it versatile for different projects.

It is commonly used in home automation, industrial control systems, and IoT applications.