Many companies and organisations collect data to improve their information and products. Skills in collecting data can make this process more efficient and reliable.
The population of a survey is everyone who can be questioned in relation to that survey. For example, if a shop wanted to know the opinion of a new marketing strategy, the population of the survey would be everyone who lives close enough to use the shop. A sample is a small selection of the population.
There are advantages and disadvantages to using entire populations and samples.