Stars are always there, even during the day! It's just that the sun's light is so much brighter that it washes out the stars' light during the day.

Here's what happens:

* As the sun sets: The sky starts to get darker, and the brightest stars become visible. This is usually around sunset.

* As it gets fully dark: More and more stars become visible until the sky is full of them. This is usually around astronomical twilight, which is about an hour after sunset.

So, while stars are technically always out, you can only see them at night when the sun's light isn't overwhelming them!