Database:an organized collection of information,
usually pertaining to a particular subject.
Think of databases as huge electronic filing systems. They must be highly organized for people to easily find the information they need.
There are many kinds of databases. The most common type you will encounter in the library is an online periodical index, which points you to articles published in magazines, journals, and newspapers.
Each year millions of articles are published in periodicals, some of which are indexed in periodical indexes. Your library will probably own many -- but may not own all -- of the periodicals included in those indexes.
When you search a periodical index you will always get a citation, which includes the article author, article title, magazine or journal title, and date. Sometimes you will also find abstracts or the full text of articles.