**Note: This may not be the correct forum for this post; I posted here as I thought it may be related in at least an indirect way. Please move if necessary.
I have never knowingly worked on any projects where I had to attempt to extend a language. I hear this concept thrown around, but I do not have any concrete concept of implementing this. I am not at this time in need of doing this but I believe it is inevitable at some point to be able to at least understand it better. I have done research via the 'Net but only find what I consider vague definitions and examples.
As an over-view at this point, I would define "extending" a language to be taking options available in one language (say for example "C") and using them to enhance another language such as Python, for example.
I have read that Python and Perl are considered "glue" languages used to, "tie together systems and interfaces that were not specifically designed to interoperate"-- I am not sure if this would be included in a general definition of extension although I assume it would.
I am seeking a general insight into this and perhaps a non-coded example(s) of how this might be practically implemented and why. I will then be able to further research this topic and work on some basic, coded examples to learn from.
Thank-you for your time and any help offered.