Word creates an index by marking words you choose, then collecting them in alphabetical order at the end of your document

An index is a list of terms and the page numbers where they appear. Microsoft Word does the page-number tracking automatically once you mark the words you want included. You mark words as you write or edit, then tell Word to generate the index in one step. The index appears wherever you place your cursor, usually at the back of a document.

This is different from a table of contents, which lists headings and sections. An index lists specific terms — the words that matter most to your reader's understanding. If you are writing a technical manual, a textbook, or a long report where readers might search for particular concepts, an index saves them from flipping through pages.

Key Takeaways

  • Mark index entries by selecting a word, opening the References tab, and clicking Mark Entry — each marked word can point to multiple pages if it appears throughout your document.
  • Word stores marked entries invisibly in your document; deleting the visible word does not remove the index entry, so you must delete the entry code itself.
  • Generate the index by placing your cursor where you want it to appear, clicking References > Index, and choosing a style — Word then collects all marked entries in alphabetical order with their page numbers.
  • If you add or delete pages after creating the index, right-click the index and select Update Field to recalculate all page numbers automatically.
  • Marking entries takes time upfront, but prevents you from manually typing page numbers or forgetting terms readers will search for.

Mark words before you generate the index

Open your document in Word and find the first word you want in the index. Select it by clicking and dragging or by double-clicking the word. Then go to the References tab at the top of the screen. Click Mark Entry (or press Alt+Shift+X). A dialog box opens.

The word you selected appears in the Main entry field. You can leave it as is or edit it — for example, if you selected "photosynthesis" but want the index to list it as "photosynthesis, process of", you can type that in the field. Click Mark to mark this single instance, or click Mark All to mark every instance of that word in the entire document. Most people click Mark once per location, because the same word might need different context depending on where it appears.

After you click Mark, the dialog stays open so you can move to the next word. Close the dialog when you are done marking. Word has now hidden index codes in your document — you will not see them unless you turn on formatting marks (Ctrl+* on Windows, Cmd+* on Mac).

Mark entries with subentries for more detailed organization

If your document covers a broad topic with many related terms, you can organize the index with main entries and subentries. For example, instead of listing "apple," "orange," and "banana" separately, you could list them under a main entry called "Fruit."

When the Mark Entry dialog is open, type the main entry in the Main entry field and the subentry in the Subentry field. If you want "apple" to appear under "Fruit," type "Fruit" in Main entry and "apple" in Subentry. The index will then show:

Fruit   apple, 45   orange, 67   banana, 89

Subentries are optional and work best when you have many related terms. For a short document, a flat index with just main entries is clearer.

Generate the index after marking all entries

Once you have marked all the words you want, place your cursor at the end of your document or wherever you want the index to appear — usually on its own page. Go to the References tab and click Index. A gallery of index styles appears. Click the style you prefer. Word inserts the index when ready, showing all marked entries in alphabetical order with their page numbers.

The index is a field, not plain text. If you click on it, you will see it is shaded gray (or outlined, depending on your view settings). This tells you Word is treating it as a live field that can be updated.

Update the index if your document changes

If you add pages, delete pages, or move text around after creating the index, the page numbers in the index become wrong. Right-click anywhere in the index and select Update Field. A dialog asks whether to update page numbers only or the entire index. Choose Update entire index to catch any new marked entries you may have added. Word recalculates all page numbers in seconds.

If you add new marked entries after the index is created, updating the index will include them. If you delete a marked word from your document, the index entry remains until you manually delete the entry code — selecting and deleting the visible word does not remove the hidden index marker.

Delete or edit index entries

To remove a single marked entry, turn on formatting marks (Ctrl+* on Windows, Cmd+* on Mac) so you can see the hidden codes. Find the entry code — it looks like { XE "word" } — and delete it. The word stays in your document, but it no longer appears in the index.

To edit an entry after the index is generated, find the hidden code and change the text inside the quotation marks. Then update the index. For example, if the code says { XE "apple" } and you want it to say "apple, red variety," change it to { XE "apple, red variety" } and update the field.

Deleting the entire index is straightforward: click anywhere in the index, right-click, and select Delete Field. The marked entries remain in your document, so you can regenerate the index later if you change your mind.

Avoid common mistakes when building an index

The most common mistake is marking entries too late. If you wait until your document is finished, you may forget important terms or miss instances where a word appears. Mark entries as you write or during a dedicated editing pass where you read through specifically to identify index terms.

Another mistake is marking too many words. An index with every noun listed is not useful — it becomes as long as the document itself. Choose terms that a reader would actually search for: key concepts, proper names, technical terms, and important processes. Skip common words like "the," "and," or "document."

A third mistake is not updating the index before printing or sharing. If you moved text or added pages and did not update the index, the page numbers will be wrong. Always update the index as your final step before you finish.

Frequently Asked Questions

Can I mark a phrase instead of a single word?

Yes. Select the entire phrase you want to mark — for example, "machine learning" or "climate change" — and follow the same steps. The Mark Entry dialog will show the full phrase, and you can edit it if needed. The index will list the phrase exactly as you marked it.

What if the same word appears on multiple pages?

Word lists all page numbers where you marked the entry. If you marked "algorithm" on pages 12, 34, and 56, the index shows "algorithm, 12, 34, 56." You do not have to do anything special — just mark the word each time it appears, or use Mark All to mark every instance at once.

Can I change the index style after I create it?

Yes. Delete the current index, then insert a new one and choose a different style from the gallery. Your marked entries remain, so the new index will include all the same terms. You can switch styles as many times as you want without losing your work.

Does marking entries slow down Word?

Not noticeably. The hidden codes are small and do not affect performance. Large documents with thousands of marked entries may take a few extra seconds to update the index, but the difference is minimal on modern computers.

What happens to the index if I convert the document to PDF?

The index converts to a static list in the PDF — the page numbers stay correct, but the index is no longer a live field. Readers can still use it to find pages, but you cannot update it from within the PDF. If you need to make changes, edit the Word document, update the index, and export to PDF again.