Legal Definition
IRS stands for the Internal Revenue Service, which is the U.S. federal agency responsible for collecting taxes from individuals and corporations. It is the governmental body that administers and collects federal taxes, including income taxes, and provides tax services to the citizens of the United States.
Plain-English Translation
The IRS is the government office that makes sure everyone pays their taxes. It's the place where people and companies pay money to the government so they can pay for things like roads, schools, and military. It's the boss that collects all the taxes.