The complete set of individuals or items under study, from which a statistical sample is taken for the purpose of estimating a numerical characteristic, or to make an inference about that set. When the appropriate sampling method is used (ensuring that the sample is representative of the population), conclusions from the sample may be generalized to the population.
In a study of the effect of a new type of braking mechanism on electric golf carts, the population comprises all electric golf carts.
A population doesn’t have to physically exist. It could be hypothetical, such as the population of values obtained if 10 dice were tossed simultaneously.