From Teflpedia

A publisher is a company that publishes books.

ELT publishers include:

See category:publishers

It has been widely noted that as commercial companies, the purpose of a publisher is to make money for its shareholders. Although this often aligns with publishing high quality, useful materials, it does not always.

Corporate acquisitions, splits and mergers, bankruptcy, imprints, rebranding, etc. can make information about companies hard to track.