Tropicans are people that live on your island. They are usually either born on the island or immigrants to Tropico. They are independent members of the community with their own personal preferences, desires, and choices.
Any way about it, they consume your food, live in your housing, spend your wages, and work your jobs.
Dealing with One's Tropicans
Tropicans need you - for many things. They need you to issue them jobs so they can earn wages to buy food, buy entertainment, and pay for rent. They need pubs, restaurants and other venues for their entertainment, marketplaces and farms for food, churches and cathedrals for religion, and many, many other things. Not satisfying the needs of your Tropicans can result in unhappiness, ditching work to fulfill their needs, or even rebellion!
They also need a Presidente. You can be their presidente if they elect you for years on end, or if you force your rule on them using underhanded edicts and force.
The former idea makes the people happier, but leaves your power at their will.
The latter ensures your power for as long as you have the manpower to enforce your will (though a coup d'état may bring your reign to a sudden end ...).
Whatever you do, your Tropicans will respond in their thoughts, which are a dedicated tab whenever you select a Tropican. The Tropican's thoughts range from useful (what they need, whether they're happy with the current reign and other concepts) to funny (One day I will go to America and work for Poptop!)
How the Tropican Mechanic Works
Unlike most other simulation games, where the people are attached to the buildings (good example: Simcity series), Tropico has the buildings attach to the people. A person has a home (and not the other way around), a workplace, and even entertainment places. Tropicans are simulated as real human beings. They'll leave work at what you may see as the most inconvenient times. A building may be 95% finished, but the builder suddenly leaves! Why? Those people have feelings and needs too. If they need to eat, they'll drop everything and head to the nearest farm or marketplace to make sure they live another day. Don't despair though! Tropicans will only leave their job if their need bar is extremely low. Other than that, they'll work dutifully and loyalty. Outside of work hours (yes, you sometimes have the option to have limited control over some building's work hours), Tropicans will doze around, try to satisfy their needs, or even meet a spouse and get married. This is where Tropico really shines. People don't just appear out of nowhere (although immigration sometimes appears to be like that; people poof out off the dock). They either emigrate from another country (bringing their beliefs and joining the island's factions) or are born from people already on the island (inheriting the beliefs of their parents). Immigration is so important, it gets its own building (so you can set how emigration and immigration work).
Tropicans also have factions, which make the game even more complex.