Keep the lamp still
We have day and night because Earth rotates. A place has daylight while it faces the Sun and night while it faces away. Picture a globe beside a lamp: put a sticker on the globe and slowly turn it.
When the sticker faces the light, its place is in daytime. When it turns away, that place is in nighttime. The Sun does not need to circle Earth every day for this change to happen: Earth rotates.
Try it yourself
Place a sticker on a globe or ball and shine a lamp from one side. Slowly turn the ball while leaving the lamp still. Watch the sticker move into the light and back into shadow.
This lamp-and-ball example is a model, not a live map or a sunrise forecast. It leaves out latitude, the atmosphere and the tilt of Earth. Those details affect real daylight, but the simple model makes the daily turning easier to see.
A spin and a journey
A rotation is a turn around an axis, like the globe spinning on its stand. An orbit is a journey around another object. Earth rotates while it also travels around the Sun.
A solar day is about 24 hours; Earth’s trip around the Sun takes about a year. Mixing up these two motions makes it hard to explain why night happens every day while seasons change over months.
Why someone else is awake
Two places on different sides of Earth do not face the Sun at the same time. Your evening can be someone else’s morning. Clock systems help people organise this difference, but the turning Earth comes first.
Next, move the lamp-and-ball idea to the Moon. Half of the Moon is normally lit by the Sun too, yet the amount of that lit half visible from Earth changes through the month.