Answer:
For Birth
1.Be born on U.S soil, any territory, U.S. ship(mIlitary), and a U.s. Embassy/military base
For foreigner:
Serve in the military for a set number of years, Apply for an H1B(work visa), or the other types of visa, then get an EID/Greencard keep the greencard for 5 years and take an oath and bam US citizenship