What is the example for a black body?

A classic example of a black body is a perfect black surface that absorbs all incident electromagnetic radiation, regardless of frequency or angle, without reflecting any light. In practice, a common approximation of a black body is a small hole in a hollow, opaque cavity; the hole allows radiation to enter but minimizes the escape of light, making it behave like an ideal black body. Additionally, stars, including our Sun, can be closely modeled as black bodies due to their emission of thermal radiation across a spectrum of wavelengths.