Here's why:

* Solar Day: The time it takes for the Sun to appear in the same position in the sky, roughly 24 hours. This is what we experience as day and night.

* Sidereal Day: The time it takes for the Earth to complete one rotation relative to the distant stars, about 23 hours and 56 minutes.

Why we use solar days:

* Our lives are influenced by the Sun. The Sun provides light and warmth, and our daily rhythms are synchronized with its cycles.

* Solar days are more practical. It's more convenient to measure time based on the apparent movement of the Sun, which directly affects our day-to-day activities.

While sidereal days are important for astronomy, they aren't practical for everyday life.