It’s 10 p.m. Your cellphone knows where you are. It also knows where you are at 10:00 in the morning, at 7:00 in the evening, and at noon and midnight and at every other moment of the day.

We live in a world where cellphones are omnipresent. We have them at home, at work, and everywhere we go other than home and work. The cellphone may be the product that is more a part of our daily lives than any other.