If the labour force is one of the engines that power the economy, foreigners are a key ingredient of the fuel that drives the engine.
The numbers tell the story.
There are 1,368,200 foreigners working in Singapore, out of the 5.535 million population and 3.531 million workers in the labour force.
This means that about one in four people here is a foreign worker. And about two in five workers here are foreigners.
The numbers will be even higher if permanent residents are counted as foreigners. Statistically, they are considered part of the resident population and workforce. Foreigners do anything from manual tasks such as clearing the rubbish chutes to top-rung work like running the Asian operations of multinational companies based here.
The inflow of foreign workers has been tightened in recent years, but their numbers are still inching up.
The Ministry of Manpower does not publish a breakdown of the nationalities of foreign workers here or statistics on the number of foreign workers who leave Singapore each year.
But since foreigners work here on renewable work passes that are typically of between one and three years, and assuming that 20 per cent of them - or 274,000 - leave each year, some 2.7 million of them would have worked in Singapore in the past decade.
How has working in Singapore made a mark on their lives? To mark International Migrants Day on Friday, our reporters met four foreigners who have worked here.
They are a maid from Indonesia, a former welder from Bangladesh, a recruiter from China and a car-company executive from Britain.
They talked to Insight about their experiences of working and living in Singapore and how the stint changed them.
The maid from Indonesia
As a teenager alone in a foreign country, Indonesian maid Nova Erni Esiana Bones cried almost every day for the first month after arriving in Singapore.
With no mobile phone and no friends, all she could do was to think of home and her parents - the left-behind drivers of a dream.
Seven years later, she is still working as a maid, but in Bali, Indonesia - and she now soothes the cries of her baby girl who cannot bear to lose sight of her.
The ship welder from Bangladesh
At his welding job in a garment factory in Bangladesh's capital of Dhaka, Md Shahabuddin fuses together steel sheets, repairs iron pipes and works in searing heat - with his bare hands.
For nine hours a day, six days a week, earning the equivalent of $280 a month, the 45-year-old father of three goes about his dangerous duties, his mind on Singapore.
"I think about going back (to Singapore) all the time," said Mr Shahabuddin, who worked as a welder for an engineering firm in the Republic between 2006 and 2008 for $600 a month. "The money was good, hours were good."
The recruiter from China
The most difficult choice that Chinese national Wang Cheng Jun ever had to make was leaving Singapore.
Mr Wang and his wife Zhang Li- min, also from China, had spent three happy years working and living together in Singapore. He was a recruitment agent, initially as an S Pass holder before gaining an Employment Pass, and she was on an S Pass as a nurse.
But the birth of their first son in 2013 turned this life upside down.
The car company exec from Britain
When Singapore celebrated SG50 in August, a family living in the village of Wellesbourne, Warwickshire, about a two-hour drive north-west of London, also celebrated the Republic's National Day.
The family wore clothes in Singapore's national colours of red and white the whole day, and had kaya toast for breakfast, noodles for lunch and fried rice for dinner.
They are not Singaporeans, but British nationals Dan Balmer, 39, his wife Michelle, 35, and their daughters Ella, 10, and Eva, five.