Keyword searching is used by internet search engines, databases, and the library catalog, although there are some differences in how such searches function. Keep in mind that the search will find matches for specific terms, not concepts.
Most search engines' algorithms take into account the term order. Library databases do not! Databases also have much more advanced searching--including subject searching. A database search will search for EXACT character string matches (PubMed is an exception.)
Check out the menu "sub-page" buttons under Search Strategies for some basic search functionalities common to library resource keyword searching. We will look at these more fully in the recommended databases.
Keep in mind: Databases search the database record of the article (title, abstract, authors, etc.), most do not search within the full text of the articles.
The default in many library databases is to find results that include every word in a basic search. Think of this as using AND between the words:
An AND search generates results for that include ALL of the AND-ed terms.
Think of subject headings as labels or tags that someone has used to identify the subject of a book or article. The subject headings are standardized so that only one term is used for a specific subject. They work similarly to #hashtags in Twitter, subject headings categorize and pull together all articles on a topic.