Wave-particle duality is an important idea in modern physics. It shows that light can act like both a wave and a particle.

Photons: When we talk about particles, we refer to photons. These tiny units carry energy, and we can find this energy using the formula $E = hf$. In this formula, $h$ is a constant named Planck's constant, and $f$ stands for frequency. This concept is very important for new technologies like lasers and solar panels.

Applications: Knowing about wave-particle duality has helped scientists make big strides in quantum mechanics. This knowledge has led to amazing tools like quantum computers and special imaging systems, like MRI machines.

So, wave-particle duality is really important in both theory and real-life physics.