[Torwald]

Elisp, but not really elisp, more the environment of elisp. It's a LISP machine. Hard to explain, it's a different way of computing. Another living instance of this model of computing is a Smalltalk image. Others have written about how LISPing makes you a better coder much better than I could. Try it out!

[codethief]

I disagree, Elisp doesn't tie org to Emacs at all. What does tie org to Emacs is the fact that Emacs' org-mode (i.e. the mode you use to edit org files) provides a great DevEx when editing org files, including lots of convenience shortcuts. (Again, the fact that those are written in Elisp is irrelevant.)

[skydhash]

It does. A lot of advanced options in Org have escape hatches for more code, and the fact that you configure org in Elisp and are free to hack on org provided functions due to the Elips environment add to its versality.