There are several ways to get a second citizenship and the corresponding passport, including citizenship by ancestry, citizenship by residence, and citizenship by investment.
A portion of countries offers non-residents an opportunity to obtain a second citizenship if their parents were born in the country. For instance, a European country Hungary allows people not living in the country to obtain Hungarian citizenship provided that they can prove the Hungarian citizenship of their parents.
Naturalization is the procedure through which a country resident can acquire citizenship. Usually, citizenship can be acquired by permanently residing in the country for a certain amount of time. One of such examples is Canada, whose permanent residents must live in Canada for four out of six years to be eligible for citizenship.
Nowadays, more and more countries offer citizenship by investment. This term refers to the process of acquiring second citizenship by investing in the economy of the host country.
A married person can also automatically count as a citizen of their partner's country in certain parts of the world. Children may automatically have the parent's nationality as well, even if they were born abroad.