A short history lesson
Once upon a time all files were stored on magnetic tape and all access was sequential.
Then came the disk drive and random access and there was joy in the land! But you know, because your parents told you,
that too much of a good thing is bad for you. And so it is with random access - unless you organize your data it will be so randomized
that you'll never find it again.
So, somebody came up with a way to store large amounts of data in such a way that it could be updated and retrieved when needed.
They called the structure containing the data a database
and the programs doing all the
administrative work of handling the data a Database Management System (DBMS)
The first databases were modeled upon COBOL data structures (in those days every programmer was a COBOL programmer)
and were called hierarchical
because of the way in which the data are structured.
Eventually they improved upon the first model and came up with a network
which has absolutely nothing to do with Novell or NT, but describes the way the data elements relate to one another.
Some of those large databases are still in use today in legacy applications all over the place.
In the early 70's Dr. E.F.Codd, who happened to be a mathematician rather than a programmer, came up with a new model he called relational
This relational model, built on the mathematics of set theory, was powerful, flexible and easy to use.
But it turned out to be such a hog for disk space and processing time that it wasn't really a viable alternative to the previous models. It wasn't until hardware performance improved in the late 70's that the model started gaining acceptance.
By the mid 80's, cheap PC's with ever-increasing capabilities made it possible to develop small versions of relational databases.
It was Oracle Corp. that really put relational database development on the map and today Oracle is still the leader in the field.