The Domain-Specific Language (DSL) is a computer language specialized to a particular application domain. Every time you need some command-line interface, complex configuration files, or scripting requirement, the DSL metalinguistic abstraction takes its play.
There is a special case the embedded Domain-Specific Language (eDSL) when you are extending your host language in which you are mostly working (Elixir), with some extra abilities specific to your tasks.