I'm aware that some "temporary" LaTeX dimensions etc. exist. I would, however, like to know all of them. I know \reserved@a (macro), \@tempdima (dimension) and \@tempcnta (counter).
Let's see the following screenshot taken from an answer of Efficient ways to anonymize a document and the given comment. Is it possible to remove length, counter, dim, etc, that have been declared ...
What are the differences between \newdimen, \newskip, and\newlength? When should I use each of them? Please give me a non-trivial example for each case.