## TL;DR
Neuroplasticity — the brain's lifelong capacity to reorganize structure and function — is the biological basis of learning, memory, and recovery from injury.

## Core Explanation
Plasticity operates at synaptic, cellular, and systems levels. Hebb's rule — "neurons that fire together, wire together" — captures the associative principle underlying LTP. The adult brain generates ~700 new neurons daily in the hippocampus.

## Detailed Analysis
Environmental enrichment — exercise, cognitive stimulation, social interaction — upregulates BDNF, promoting plasticity. Constraint-induced movement therapy exploits plasticity to rehabilitate stroke patients by forcing use of the affected limb.

## Further Reading
- Society for Neuroscience: BrainFacts.org
- Nature Neuroscience
- Allen Institute for Brain Science