From the fine document: Micro-typography is the art of enhancing the appearance and readability of a document while exhibiting a minimum degree of visual obtr

From the fine document: Micro-typography is the art of enhancing the appearance and readability of a document while exhibiting a minimum degree of visual obtrusion. It is concerned with what happens between or at the margins of characters, words or lines. Whereas the macro-typographical aspects of a document (i.e., its layout) are clearly visible even to the untrained eye, micro-typographical refinements should ideally not even be recognisable. However, there don't seem to be any major changes to the package since 2021. (Which is not surprising, since it was first released in 2004.)