Learn in the textbookDatabase and DBMS Basics, and Types of NoSQL
DefinitionNoSQL is an umbrella term for databases that hold data in forms other than the tables of the relational data model.
ExplanationThe name is usually read as "Not only SQL," and it refers not to one product but to several types that hold data in different ways. Many of these types do not require table columns to be fixed in advance, and they are used for data whose shape varies or for large volumes of data spread across many servers.
AnalogyIf an RDBMS is manuscript paper with a fixed grid, NoSQL is a stationery shelf holding plain notebooks, flashcards, sticky notes and more.
Memory hookNo is usually read not as "no" but as "Not only." Read that way, the name does not reject SQL; it admits ways of holding data other than tables.