Answer:
There are 24 time zones around the world. They have been created based upon their distance from the Prime Meridian. In this situation, my friend and I are in different time zones. This means that, as the Earth rotates, our locations, LA and Riyadh, are in different positions in relationship to the Sun. Riyadh is far east of Los Angeles. Its time zone moves toward the sun 10 hours ahead of LA's time zone. So, when it is 10:00 in the morning in Riyadh, it is only midnight in Los Angeles. Understanding time zones makes it easier to communicate with people who are in different parts of the world.