[meej]

This is a good basic overview, goes beyond tagging/indexing, was the textbook in LIS501 Information Organization and Access at UIUC-GSLIS (now the iSchool at Illinois) in 2006:

https://mitpress.mit.edu/9780262512619/the-intellectual-foun...

Controlled vocab standards:

https://www.niso.org/publications/ansiniso-z3919-2005-r2010

(this one is deprecated in favor the one that follows)

https://www.niso.org/schemas/iso25964

https://www.w3.org/2004/02/skos/

The book we used in my thesaurus construction class at UIUC:

https://www.alastore.ala.org/content/essential-thesaurus-con...

My favorite intro to semantic modeling with RDF/OWL/SPARQL:

http://workingontologist.org/

Topic Maps are dead but i still have a soft spot for them:

https://www.isotopicmaps.org/

I also recommend Heather Hedden, linked in jrockhind's post.