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 export it as a PDF or EPUB document. You can even ...

You can make a table of contents in a Google Doc with a computer or iPhone, and create organized navigable sections for readers.

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

Inserting a table of contents in Microsoft Word provides an overview of the content. Here’s a guide on how to create a table of contents in Microsoft Word.