Hebbian learning is a theory in neuroscience that explains how connections between neurons strengthen when they are activated together. This principle is often summarized by the phrase "cells that fire together, wire together." It suggests that repeated activation of certain neural pathways enhances their efficiency, leading to improved communication between those neurons. This learning mechanism is fundamental to various processes, including memory formation and skill acquisition. It helps the brain adapt and reorganize itself based on experiences, making it a key concept in understanding how learning occurs in both biological systems and artificial neural networks.