# The singleton set and the unit type¶

The singleton set from set theory corresponds to the Unit type from type theory. Also to `true`

in logic, and to a 1-category in category theory.

## Backlinks¶

- Video Series: Category Theory
- The singleton set
- The singleton set has a single element. It corresponds to the unit type in type theory.

- Dual
- It is related to the singleton set from set theory and dual to the void type

- Unit Type
- It is related to the singleton set from set theory and dual to the void type