The world population has grown significantly over the past 2000 years, reaching over 7.2 billion in 2014 and expected to hit 8 billion by 2025. China is the most populated country, followed by India and the United States. This growth is mainly due to more people reaching reproductive age, changes in fertility rates, urbanization, and migration. These trends will have long-lasting effects on future generations. World Population Day is celebrated on July 11th to raise awareness about global population growth and related issues.