Observed on July 11 every year since 1989.
From Census.gov > Data > Data Tools > U.S. and World Population Clock > Notes on the World Population Clock:
The populations displayed on the clock are not intended to imply that the population of the world is known to the last person. Rather, the clock is the Census Bureau's estimate of the world population size and an indication of how fast it is growing. According to current estimates, the world population reached 7 billion in 2012 and new projections indicate that the 8 billion marker will be reached in 2025.
Note: The International Data Base (IDB) was developed by the Census Bureau to provide access to accurate and timely demographic measures for populations around the world. The IDB provides estimates and projections for 228 countries and areas which have populations of 5,000 or more and as recognized by the
U.S. Department of State. The IDB estimated the world population reached 7.5 billion on June 13, 2018.
From Census.gov > Our Surveys & Programs > International Programs:
The U.S. Census Bureau conducts demographic, economic, and geographic studies of other countries and strengthens statistical development around the world through technical assistance, training, and software products.
Note: Visit the IDB Help page for more information.
Source: Demographic estimates prepared by the Census Bureau's Population Division for the International Data Base.
About International Map Viewer: Introduction: This viewer provides four 2021 demographic indicators for the world's countries with a minimum population of 5,000 in 2021: total population, growth rate percent, life expectancy at birth, and infant mortality rate.