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# About relational databases
## What is a relation?
A common misconception is that the "relations" in a relational database are about relations between database tables.
Actually, the relations in a relational database are the tables.
A relation "relates" a set of values with another set of values.
For example, a relation can relate the name of a person with their birth date and birth place.
For example:
```
(person name) => (birth date, birth place)
(Alice) => (1979-12-03, Barcelona)
(Bob) => (1995-03-04, Paris)
...
```
Many computer languages have similar concepts:
* [Python mapping types such as `dict`](https://docs.python.org/3/library/stdtypes.html#mapping-types-dict)
* C++ `std::map`
* Java `java.util.Map`
* [C# `System.Collections.Generic.Dictionary`](https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2?view=net-9.0)
* [Javascript `Object`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)
* [PHP arrays](https://www.php.net/manual/en/language.types.array.php)
Relations are a natural concept, so although non-relational data systems exist, most data can be stored as relations.
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