How many hours are there in one day?

In one day, there are 24 hours, which is a standard unit of time measurement. This division arises from the fact that the Earth takes approximately 24 hours to complete one full rotation on its axis, leading to the cycle of day and night. Thus, we conventionally define a day as lasting 24 hours, which is further subdivided into 60 minutes each, and each minute consists of 60 seconds. This time measurement is universally recognized and is a basic concept in both daily life and various scientific disciplines. Therefore, the answer of 24 hours is accurate and aligns with standard timekeeping conventions.