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Ever since its formation around 4.5 billion years ago, Earth's rotation been gradually slowing down, its days have gotten progressively longer as a result. Earth's slowdown not noticeable on human timescales, it's enough to work significant changes over eons. One changes is perhaps most significant of all, at least to us: lengthening days are linked to oxygenation of Earth's atmosphere, a study from 2021.

Specifically, the blue-green algae (or cyanobacteria) that emerged proliferated about 2.4 billion years ago have been able to produce more oxygen as a metabolic by-product because Earth's days grew longer. Check out the video below for a summary on the research.

Earth rotates on its axis, completing one spin every 23.9 hours with respect to the Sun, but 23 hours, 56 minutes, and 4 seconds with respect to distant stars. This rotation is what causes day and night, and also affects the Earth's magnetic field. The Earth's axis is tilted 23.4 degrees from the plane of its orbit around the Sun, which causes the seasons.

Here's a more detailed look:

Rotation Speed:
The Earth's rotation speed is relatively slow compared to other planets, meaning the Coriolis effect, which is a consequence of the rotation, is not strong enough to be seen at slow speeds over short distances.

Direction:
The Earth rotates eastward, in a prograde motion, meaning it spins in the same direction as the Sun's rotation. This is why the sun and stars appear to rise in the east and set in the west.

Axis Tilt:
The Earth's axis is tilted at a 23.4-degree angle relative to the plane of its orbit around the Sun. This tilt causes the seasons, as different parts of the Earth receive more direct sunlight at different times of the year.

Rotation and Day/Night:
As the Earth rotates, different parts of the planet are exposed to the Sun, creating the cycle of day and night.

Rotation & Magnetic Field:
The Earth's rotation, combined with the molten iron in the planet's core, generates a magnetic field that protects us from harmful solar radiation.