Keyword searching is generally what you use when you begin a search. Keywords will be the main ideas in your research question or topic--typically the nouns--people, places, ideas, things.
Keywords have a profound impact on search results. Using the right words will speed up the research process; choosing the wrong ones can bring the search to a painfully screeching halt.
It helps, too, to have synonyms for your keywords. There's usually multiple terms you can use for a concept.
Take, for example, the use of Ritalin in adolescents to improve grades.
How does one think of synonyms? Run your search first. Look at your good results. Generally within your good results, you'll see other terms being used that you can pull into your search. OR...run a Google search on your words. Or run a search of your words in a Thesaurus. Or use the keyword generator tutorial.
You may also want to think of narrower terms or broader terms, too, depending upon how many results your search is generating.
Another way to think of keywords is to use mind maps.
Subject terms are a form of descriptive metadata. At their simplest they may be tags chosen by the authors, but most databases use a controlled vocabulary assigned by professional catalogers. Subject terms may also be called index terms, MeSH, subjects, subject headings, etc...
The advantage of subject terms is that they're standardized terms which will be assigned to all content covering that topic. So no matter what terminology or language is used by the author, the same subject term will be used.
For example, Academic Search Ultimate uses the subject term "Gender Wage Gap". Again, even if the article's author uses the keywords pay inequality or wage gap or gender pay gap or equal pay, a subject term search of Gender Wage Gap will retrieve all of the articles on that topic.
Whenever you find a good article in a database, check out the subject terms. If one or more of them look like matches for your topic, re-run your search using those subject terms--and be sure to specify you want those terms in the subject field. That will ensure the search results are really about that subject and don't just contain that word in the record (but aren't really about it).
One thing to watch out for: Each database has its own controlled vocabulary for subjects. This means that if you do use subject searches, you'll need to discover the subject term for your topic in each of the separate databases.
Subject Term for Gender Wage Gap
|Gender Studies Database||
|Academic Search Ultimate||
|SOCIndex with Full Text||
As you can see, the usefulness of the subject headings can vary, particularly if you're searching across multiple databases. And remember that EBSCO is not a database. It is online publishing companies that hosts multiple databases. So even though you can search multiple EBSCO databases from the same search box, the subject terms won't be consistent.
It's important that you understand exactly what the databases are searching.
Most databases do not actually search and contain the full text of all of the articles. Instead they contain/search metadata.
Metadata is data about the data. It summarizes (and organizes) basic information about the data. Doing this makes finding particular instances of data easier.
Common metadata organizational fields that are searched with a keyword search:
Choosing the right search field can be crucial. You'll get very different results searching "shakespeare" as an author vs. searching it as a subject or within the title field.
Searching purely full-text databases (that is, databases that do not have metadata) successfully can be challenging. This is because you are searching the full-text of everything contained within the database. Full-text searches retrieve huge numbers of results, many of them irrelevant.
You can focus full-text searches by using a "phrase search" (putting quotations marks around words that normally appear side by side) or by focusing your search within a particular field, i.e. title or abstract.