Have you ever wondered, why Google and other search engines guide you to appropriate Web pages and submit proposals, even though they don't contain the searched terms?
Correct: search engines and searchers are led by indexed web pages and by keywords and synonyms contained in the metadata
Any reader, who has already searched in a specialist book for contexts, can tell youa thing or two about bad book indexes.
And what makes up a good book index? A good index leads readers to the right places, without knowing the terminology of the author.
Terminology work can therefore support and increase the hit rates of your Web pages and facilitate the indexing of these pages.