The concept of citizenship has been around for millennia, as ancient Greek states like Athens pioneered the idea of giving individuals citizenship. Citizens in Athens had the right to own property, run for political office, vote on administrative affairs, and, also, fully contribute to the economy.

Citizens now have full rights within their country, but their status comes with responsibilities such as avoiding any criminal conduct, contributing to the economy, and, what's more, respecting the rights of other citizens.

Many consider getting a second citizenship a complex process because most of the routes to becoming a dual citizen are quite long or demand extremely specific requirements. Here are the main routes to acquiring a second citizenship:

• Naturalization is the most common, and longest, route to obtaining a second citizenship. This occurs when a person spends a specific amount of years as a resident of a nation until they can apply to become a citizen under the host country's laws.
• Citizenship by Marriage is another way to acquire another nationality. In most countries, if you marry a citizen of that nation then you are eligible to apply for citizenship. You can do this directly or after obtaining a residence permit and then becoming a citizen through naturalization.
• Citizenship by Descent is a fairly simple, but extremely exclusive, route. Countries such as Austria, Ireland, Italy, Poland, and Portugal offer people with ancestors who were citizens of their nation the chance to apply for citizenship. However, proving ancestry can be a complex process depending on the documentation required, and it is very specific to a small portion of the world's population.
• Exceptional Citizenship is an extremely rare occurrence. It is usually granted to high-profile people like Tom Hanks. The famous actor obtained Greek Exceptional Citizenship for his charity work in the country.
• Citizenship by Investment is the simplest option. Many countries offer investors the chance to obtain citizenship through investing in a nation's economy. It is the fast track to a new nationality.

The idea of Citizenship by Investment also stems from ancient times, and the Roman Republic was the first nation to develop it into a route to citizenship. Those who contributed to the Roman economy under specific requirements were granted citizenship and all the rights that came with it, and the concept still holds true today.

Many countries now host what is referred to as Citizenship by Investment programs, which are routes to obtaining a citizenship certificate and passport of a nation through contributing to the economy. The idea is that if a person contributes to a country's economy, then they have fulfilled part of their duty as a citizen and hence should be considered one. Their other responsibilities are avoiding criminal activities and, also, respecting the laws and the rights of other citizens.

Citizenship by Investment is extremely beneficial to the countries granting citizenship, as it provides their governments with significant sums of unencumbered foreign direct investment funds to help develop the nation.

The Commonwealth Of Dominica, for example, used funds generated through its Citizenship by Investment Program to create affordable housing for its residents. The program also funds the development of the country's international airport. This is a project that will positively affect residents' lifestyles and the nation's economy as well.

Citizenship by Investment programs differ from one country to the next, but the most common types of investment usually fall into five main categories, which are:

1. Donations or contributions

Many countries grant citizenship to those who donate a minimum amount to a country's economy. The donation option is usually the simplest and most affordable route to obtain citizenship, as, in some countries, the required amount starts at as low as US $100,000. However, donations, by their definition, mean that investors do not get their money back.

Donations are usually made to government-run funds, which the government uses to develop the country. In some cases, a government may create an ad hoc fund to combat economic crisis or natural disasters, such as the St Kitts And Nevis Hurricane Relief Fund, which was a temporary route to citizenship that required a lesser donation than the then Sustainable Growth Fund due to the country having to quickly rebuild after a devastating hurricane season.

Many countries around the world offer their own version of a Citizenship by Investment program. A number of nations have a route to economic citizenship. The premise remains the same, but the requirements and processing of the programs differ from one country to the next.

However, generally, anyone who wants to apply for Citizenship by Investment must:

• Have a clean criminal background
• Provide a source of funds for their investment
• Submit a full application
• Make a qualified investment
• Be at least 18 years of age.

Malta and Antigua and Barbuda are unique in having a physical residency requirement. No other Citizenship by Investment nation requires applicants to reside or visit the country to obtain citizenship.