Computerised keyword searching allows you to find more information because the computer looks at words in the titles and content of a source as well as the subject. It also allows you to find more specific information, because each source yields many more keywords than subjects. The challenge in using keyword searching is to refine your topic so that the search yields an adequate number of useful citations. It is also important to understand the differences in the way searches are conducted by different search engines. For example, lets say you were doing a critical review on the causes of Alzheimer's diseases, and you wanted to use the net to find more information.
First lets try finding information by subject.
Find the topic Neurobiology. This can be done in one of two ways. Type in Neurobiology in the space and click on find next. Alternatively, visually scroll down the list of subjects until you find Neurobiology. You can scroll down the page by using the mouse to click on the arrow on the bar that runs horizontally down the right hand corner of the page.