To learn about the world around us, we need information. In the practice of science, several methods used to gather that information. Some of the most common methods include:
It is important to keep in mind that these are very generic categories, and that each will vary tremendously from one field of science to another. Scientists usually use several or all of these methods, comparing the results to see if they all point to the same conclusions. For example, if computer models do not fit with actual observations, that is an indication that the computer model need to be examined and refined.
It is not necessary to memorize the definitions of the different ways we gather information, but it is necessary to understand that testing the same idea with different methods is very important in science.