Basically, just the government forcing us to give a small percentage of the money we make yearly, and when they end up with a little from every American, that ends up being billions of dollars that they can spend on stuff that benefits everyone- like healthcare, care for the elderly and disabled, and military stuff.
"Taxes are mandatory contributions levied on individuals or corporations by a government entity—whether local, regional, or national. Tax revenues finance government activities, including public works and services such as roads and schools, or programs such as Social Security and Medicare." -investopedia.com