Relational databases simplify the storage and retrieval of related information. For example, rather than storing the state a person lives in a relational database might store a number to a single list of all states. Significantly, this reduces overall storage needs and makes indexing and searching significantly easier and subsequently faster.
Edgar Codd, working at IBM, introduced the idea of a relational database in a 1970 whitepaper. However, IBM failed to actually implement the technology. Eventually, various University’s created early RDBMS systems though none of them commercialized the technology.
Subsequently, a young Ampex employee named Larry Ellison became intrigued by Codd’s work. Ampex’s best days behind it and Ellison thought an RDBMS could produce enormous value at a lower cost than existing storage systems. In 1979, Ellison quit Ampex and founded Relational Software, later renamed Oracle.
Both Oracle and other RDBMS vendors battled fiercely for market share. Competing technology Sybase was doing well until gutted by private equity mania. Subsequently, they licensed their technology to Microsoft, who renamed it SQL Server, and it continues as a market leader. Informix was a contender for top database until their CEO committed fraud. He was imprisoned for only two months but that was enough to scare away customers. Open source MySQL has become a widely used RDBMS: Oracle purchased it in April 2009, for $1 billion USD.
RDBMS inventor Codd is British but he did the bulk of his RDBMS work in the US.