The Earth spinning on its axis is called its rotation. The time it takes for the planet to complete one spin is its rotation period. For Earth, this period of time is approximately 24 hours, or one Earth day.
The Earth's axis is an imaginary line running through its center of mass, and that center of mass changes slightly due to the ocean tides. Unlike some of the other planets, Earth's axis is not perpendicular, but it actually tilts about 23.5 degrees. This tilt accounts for the change of the seasons on Earth. Venus has the longest rotation period of the planets at 5,832.5 hours, while Jupiter has the shortest at 9.9 hours.