Creating pure source code files by extracting code from source blocks is
referred to as “tangling”—a term adopted from the literate programming
community. During “tangling” of code blocks their bodies are expanded
org-babel-expand-src-block which can expand both variable and
“noweb” style references (see Noweb reference syntax).
org-babel-tangle. Example applications could include post-processing, compilation or evaluation of tangled code files.