Imagine all of the articles available in all of the library’s databases. That would be a lot of articles – millions, if not more. When you search for a specific kind of article, you are taking this entire set and limiting it to only those that meet your specific criteria.
It’s useful to think of the criteria you set for your search as limits. Anything you add to build your search is a limit. If you search for articles using keywords as you saw in previous examples, you are limiting the entire set of available articles to only those that contain your keyword.
You can choose to search those keywords as specific kinds of words, like words in a title, words in an abstract, or an author word, to limit the results even further. Many databases will give you some sort of drop-down menu or check box to let you search for specific kinds of words. (If you do not see any options to do that kind of search, check the database's help information or ask a librarian.) Here is an example of limiting a keyword search to only words in article abstracts in the database Academic Search Premier:
You can also choose to limit your results to only those published on, before, or after a certain date. Look around the search screen for a place to enter a date or date range.
Many databases let you limit your results to only articles from a certain kind of publication – a scholarly/peer reviewed journal, for instance. Look for something like a check box mentioning "scholarly", "peer reviewed", or "academic journals".
These are just a few of the ways you can limit a search. Explore the database's search screen for other options. If you don't see any, look for a link to an "Advanced Search" page, which usually gives more searching choices.
With the concept of limits in mind, it is a good idea to begin your search with few limits, and add additional limits as you go along. That way, you get an idea of how much information is available related to your research and can add limits later to fine-tune your search to make the results more relevant.