Most automated robotic projects start from a line-following robot. The Grove Line finder v1.1 is designed to achieve this task easily and quickly.
Those eye-like sensors on the board are actually IR emitting LED and sensitive phototransistors. When the phototransistor detects the reflected infrared light from the IR emitting LED, it will output a digital signal, which changes from HIGH to LOW.
This module also features an adjustable detection range and indication LEDS.