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 U.S. Census Bureau's estimate of the world population size and an indication of how fast it is growing. Our latest projections indicate that the 8 billion marker will be reached in October 2023.
Observed on July 11 every year since 1989.
Note: The International Database (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 227 countries and areas which have populations of 5,000 or more and as recognized by the U.S. Department of State. The IDB estimates the world population will reach 8 billion in October 2023.
From Census.gov / Our Surveys & Programs / International Programs Center:
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 Interactive Tool Help Page for more information.