Population-
Population refers to group of individuals under study, you can understand it by an example. Suppose you have a pharmacy company and it has made a new drug
and you want see the effect of the drug on the people of country.
Here whole people of country are population for your study.
Sample-
Reality that if country is very big in terms of population like, China, India, U. S. A. and Russia then it would be very costly, time consuming and not feasible to test effect of the drug on each people.
The solution is to take some fine subset of population and conduct study.
Here finite subset of population refers to sample.
Parameters-
Parameters refer descriptive measures of population, examples are, mean, median, mode and standard deviation.
Statistic-
Statistic refers descriptive measures of sample(s), examples are, mean, median, mode and standard deviation.