Click the one you want to insert in the text. If your document has many headings, it's a good idea to add a table of contents in case it will be accessed outside Google Docs, for instance, if you ...

Word’s table of contents feature does a great job most of the time. However, when you have special requirements such as those described in this article, you might need to turn the custom options.

You can add a table of contents in Word to make your document look more professional and well-developed.

Learn how to add or insert Table of Contents in Google Docs without installing add-ons. Display index in Google Docs in two different styles.