The "swearing in ceremony" is officially called the "Naturalization
Ceremony." After the ceremony, the "new" US citizen is given a
"Naturalization Certificate" which will be used, of course, to prove US
citizenship and will take the place of a birth certificate.
This ceremony usually
takes place just prior to the Honor Graduation.
The Airmen who are not US
citizens (those who aren't born in the US or its territories) and are sworn
in as US citizens during the Coin Ceremony are called, "Permanent Resident
Aliens." In other words, they are "legally admitted immigrants" to the US.
They applied and were approved for an Immigrant VISAs to enter the US as
Permanent Resident Aliens (or PRAs). Those PRAs are allowed to live and work
in the US. They also pay income taxes and most importantly allowed to serve
in the Armed Forces of the US. Upon admission to the US, they are given and
ID card, commonly called a "Green Card" due to the slightly light green
color of the ID card. Their only responsibility is to report and verify
their place of residence (anywhere in the US) every year. After living in
the US for several years (I believe 5 years) they are allowed to apply to
become US citizens. Application to become a US citizen is a three step
process. First, the paperwork and then studying and understanding US
Constitution (specifically knowing and understanding the Bill of Rights),
knowing the 3 branches of government and how they work, second, passing the
oral interview (which will be questions about the Bill of Rights, the
branches of the government) and third, the swearing in ceremony. Ironically,
after doing all that... you have to surrender the one document that tells
everyone that you are not an "Illegal".... that's the "Green Card!"