In 1999 I started programming applications and websites. Since then I met several languages at various levels.
Each item will have its specified license, that preferably will be the BSD 2-Clause License, but some may have other licenses.
The BSD 2-Clause License have only one requirement to allow the use of the licensed object: to reproduce the copyright notice and the license text in its entirety on the source of the final object code when it is distributed, and in a way that it can be accessed by the user when the final object is compiled code. In the second case (compiled), the license reproduction can be on documentation, but must not be possible to distribute the object without such documentation.
Obviously the user is solely responsible for the use, results and consequences.