Population vs. Sample

"The term "population" is used in statistics to represent all possible measurements or outcomes that are of interest to us in a particular study."  

Examples: Cedar Crest students; trees in North America; automobiles with four wheels; people who consume olive oil

"The term "sample" refers to a portion of the population that is representative of the population from which it was selected."

Examples assuming the populations stated above: 47 Cedar Crest students chosen randomly; 8463 trees randomly selected in North America; 20 sample autos from each make (e.g., GM, Ford, Toyota, Honda, etc.); 1% of the oil consuming population per country

Source: Your textbook by Robert A. Donnelly Jr., Ph.D.