Why does hyperref overrule so many things?

Question

One very usefull package is the hyperref-package. However a lot of times this package interferes with other packages or structures within a LaTeX document.

So what is it about hyperref that makes it overrule so many things?

N.B. I have not added any specific example, because I think most of you know what I mean. For example: it very often happens that people answering a quesion write

Does (not) work with hyperref

even though the OP never mentioned the package in his question. This suggests that hyperref is indeed something special.

Answer 1

I don't think that "interfere" and "overrule" are helpful terms in this context. The hyperref package needs to do a lot of things that were never anticipated in the original design of TeX, the later LaTeX format, or many popular packages that predate hyperref (often by many years). It is therefore generally necessary to load hyperref last -- with a few well-known exceptions. See the posting Which packages should be loaded after hyperref instead of before? for a list of such packages.

As long as the stricture to load hyperref last (or almost last...) is satisfied, you shouldn't encounter harmful interference. Well, there may be some really ancient packages that are truly incompatible with hyperref; however, these packages should probably not be used anyway as newer and better alternatives are usually available as substitutes -- and which are, almost invariably, compatible with hyperref.

Answer 2

The main issue is inserting anchors, which are needed as link targets.

Answer 3

If LaTeX had been designed after the web, it would have included hyperlink functionality in its core, but it wasn't so it doesn't so hyperref has to modify parts that in an ideal world a package wouldn't be modifying.