Here's why:

* Sunlight overwhelms starlight: The Sun's light is incredibly bright, scattering and reflecting off the Earth's atmosphere. This makes it almost impossible for our eyes to pick out the faint light of distant stars.

* Our eyes adapt to brightness: Our eyes are designed to adjust to different light levels. When it's bright, the pupils constrict, reducing the amount of light that enters the eye. This makes it even harder to see faint objects like stars.

However, you can see stars during the day under specific conditions:

* From space: Astronauts can see stars during the day from space because there's no atmosphere to scatter sunlight.

* Solar eclipses: During a total solar eclipse, when the Moon completely blocks out the Sun, the sky darkens enough for stars to be visible.

* High-altitude locations: In very clear skies, at high altitudes with minimal light pollution, some of the brightest stars might be visible during the day.

So, while we don't usually see stars in the daytime, they are still there, hidden by the overwhelming brilliance of the Sun.