Abstract - one or more paragraphs that summarizes what an article is about.
Full-text - means that the resource provides you direct access to the full-text versions of some or all of its contents.
Grey literature - items that are not exactly articles--they might be reports, conference papers, manuscripts, handbooks, etc.
Index only - means that the database itself doesn't contain the full-text versions, although you can use the "Get Full Text" link to check for full-text versions in other databases.
Journal database - a database that collects together contents from many journals.
Online journal - the contents from only one topic-specific journal.
Reference database - a database containing "reference" articles, such as definitions or encyclopedia entries.
Tests & measures - items such as survey questions or other tools for gathering and analyzing research data.