Google Scholar does several things.
First, it indexes many free materials on the internet that you can use.
Second, and just as important, Google Scholar provides a very handy
citation index. A citation index shows where and when an article has been cited by other authors. Therefore, if you are interested in a book or article from 1996, you can find other related materials published later. This is a very powerful tool.
Example: Someone finds the following book interesting.

Search the subject in Google Scholar using the
Extend Search:
European Union countries Military policy. 
Selecting
"Articles and Open Archives" in the Extend Search will include
Google Scholar.
Google Scholar will show several types of results: some that are
free, others that are
pay, and others that are available through our electronic resources through the AUR Databases.

Item available through AUR Databases The second item:
Consequences of climate policy... is an article published in the journal
Third World Quarterly. To discover if this article is available through the AUR electronic resources, click on
"Journals list" in the catalog and search the
journal title (or copy & paste it).

Search the journal title.
This shows that the journal is available to us electronically, and the date of the article is also available (the article was published in 2008, while the coverage of the journal is until one year ago (as of this writing, 2009).
Citations Click on the citations to find later articles. Many times, the articles indexed by Google Scholar are available in full for free. But also notice in the right-hand column are copies of the same article that are
supposed to be available for free as full text. Realize however, that there is some spam and sometimes this will not work.

Search engines have not yet standardized their search methods, so each has its own peculiarities. Please experiment with different methods, since it is impossible to predict which ones will and will not work.
The other databases under
"Articles and Open Archives" are almost all free.
As always, if you need assistance,
ask a librarian.