Life expectancy at birth

The number of years a person is expected to live at birth, taking into account the mortality risks which apply for all separate ages in one particular year. In fact, life expectancy is an overall mortality risk for that particular year.
Life expectancy at birth in 2012 provides an indication of how long children born in 2012 can expect to live if the mortality risks do not change in the next hundred years. Because mortality risks decrease from one year to the next, the actual number of years a person born in 2012 can expect to live will exceed their life expectancy.