The Settler is a Civilian unit available from the start of the game.
Pioneers drive civilization. While most are satisfied with the status quo, happy just to survive, in every culture there are a few hardy individuals willing to strike out on their own, to risk everything in the hope of finding a better life for themselves and their children. In the past, brave settlers have led humanity out of Africa and into Europe, Asia, the Pacific, and the Americas. In the future they may lead the way to the moon, Mars, and even beyond.
The Settler is used to establish new cities. It cannot defend itself, so accompany it with a combat unit if there are any dangers around. Note that population growth in the city where this unit is being built is halted during the production, freezing on the "Stagnation" level (regardless of whether you're producing enough food or not).
A portion of surplus food is turned into production towards the Settler. The portion that is converted is significantly less once you go past a surplus of 4 Food. In a city with very few production tiles, it is advisable to have a surplus of 4 Food while building a Settler. In a city with a few production tiles, it is usually better to ignore food entirely since the city can't starve while building a Settler.
If a Settler is captured by another civilization, it will change to a Worker. This prevents you from capturing other civilizations' Settlers and using them to found new cities of your own.
Note that a city must have at least 2 Citizens before you can train Settlers there. In Gods & Kings and Brave New World, however, you can instead use Gold to instantaneously purchase Settlers.
All civilizations start with a Settler and one more unit (usually a Warrior or its replacement for that civilization). City-States also each start with a Settler, which they use on their first turn to found their actual cities. City-States cannot produce any Settlers aside from that initial one.
Unique Unit Replacements
|Horse Nomad||The Alans (Respendial)||
|Mallku||The Aymara (Tupac Katari)||
|Pioneer||Cascadia (Osborne Russell)||