1] Mark Your Index Entries. Word can build your index automatically, but it’s smart enough to know which items you want in it. So for users to create an index, they will need to mark the entries.

In the index, you want the word yacht to be the main entry and yacht names to be the subentries. It’s sounds simple enough until you try to implement that expectation.

Select the "Page Layout" tab, click the "Breaks" command in the Page Setup section, and then select "Next Page." Word will add a section break between the index and the rest of your document.