A looping counter counts up to infinity or a specific number(or possibly down to a specific number or negative infinity). Counting from 99 to 0 can be used as a simpler alternative of the 99 bottles of beer program to prove that a language is usable for computation.
Two examples are available on the page ///, printing rows of increasingly many asterisks with each run.
The looping counter was also used as the first demonstration that Black was possibly Turing-complete. (Although a looping counter does not prove Turing-completeness in its own right, it helps to demonstrate how a language is capable of storing and retrieving arbitrary amounts of data, which is often one of the hardest aspects of Turing-completeness to discover within a language.)