Keyword searching searches for those words, wherever they appear in your database - titles, subject descriptors, notes, abstracts, etc. Remember, generally you are not searching the full text of the items. You're searching the "record" of all the articles in the database's content. A "record" is a description of an item, used to give as much detail to help you determine what the content is and what it is about.
Finding the right keywords is important to directing your searches to relevant results. Search for keywords related to your topic in your readings and your articles to pull out terms that for part of the discourse on the topic. Use those to build new searches for items that you have not previously discovered.
If you are searching in some databases, it may search full text of the articles, if full text searching is available. Is restricting your searching to Full Text a good idea? This will narrow your results to only articles that particular database has full text for. Most of our databases will have the "Find it @ NU" link attached to the record, which will open the option to you to see if Northwestern has full text to that article in another database. It may be better to keep your options open than miss out on a good article.
Building a Search
There are 3 basic ways to construct a search: AND, OR, and NOT. You'll see this referred to in a lot of databases as "boolean searching".
Use AND between your terms to search for two words to appear in you your record, helping narrow your results. Unions AND labor will search for records that contain both the words union and labor. Use AND to join your topical terms.
Use OR between your terms to expand your search to include either one word or another. Trade OR Labor will search for items that contain either word. Use OR to include terms that are related or that have different spellings (labor OR labour).
Use NOT to narrow your results by removing the term from the options. China AND religion NOT Tibet will retrieve results that refer to china and religion, as long as "Tibet" is not included.
Use quotations around a two or more words to search them as a phrase. Searching for "collective bargaining rights" will make sure that your results include those two words together.
Truncating a search allows you to expand your result to include words with the same root by adding a symbol to the end of the root word, usually an *. Check the database's "help" function for the right symbol (in NUcat it is a ?). A search for Econ* will retrieve economy, economics, economic.
Be judicious with your truncation. The more letters you use, the more specific your results. Using too few letters will often result in unrelated terms. Don't use less than 4 letters.
Subject Terms and Subject Headings
Remember that most often you're searching records, not full text. Subjects, Subject Terms, and Subject Headings are used to describe what the content (article, book, etc.) is about, what it's subjects are. Subjects are more directed than keywords, as keyword searches may pull up random references to an article that isn't specifically about your topic/term.
Keywords are good to get you started on your searching, but look into the Subject Terms of articles and books that you find really speak to your topic. Use those to help expand your research.