For our purposes, a Database is an organized collection of predominantly journals article that is made easier for retrieval by specific publishers. They can be either open source and free to access to all, or behind a paywall or university library subscription. It usually contains multiple points of access like author, title, subject, or keyword.
There are general databases and specific subject databases.
Here are some examples of databases:
Scifinder-n is a specific chemistry database.
JSTOR: Global Plants is a the world’s largest database of digitized plant specimens and a locus for international scientific research and collaboration.
PUBMED is a general medical database for all health sciences including biotechnology, bioinformatics, biochemistry, etc.