Highlights
A highlight is a text selection marked with a color. Highlights have no annotation text. They are the base unit of annotation in our reader: a note is a highlight that has annotation text added to it.
Use this reference when a CS or support team member needs to explain how highlights are created, edited, synced, or removed.
Highlights are available for PDF and EPUB products only. Audiobook products do not support annotations.
Prerequisites
- The reader must be authenticated and have access to the product.
- The tenant must have annotation features enabled.
What a Highlight Stores
Each highlight saves the following data.
| Field | Description |
|---|---|
| Selected text | The exact text string the reader selected |
| Color | The highlighter assigned at creation time |
| Position | Page number (PDF) or CFI location string (EPUB) |
| Timestamp | Date and time of creation |
Highlights do not store rich text or formatting.
How Highlights Are Created
Readers create a highlight by selecting text in the reader viewport. The selection triggers a context menu with available highlighters.
Standard flow:
- The reader selects text.
- The color selection menu appears.
- The reader taps or clicks a highlighter color.
- The highlight is saved and appears inline in the document.
Quick Highlight mode:
When Quick Highlight mode is active (configured in Settings), selecting text immediately applies the currently active highlighter color without showing the color selection menu. This reduces friction for readers who work with a single color. See Highlighters for how to configure Quick Highlight mode.
Editing a Highlight
Readers can change the color of an existing highlight from the annotation's context menu inside the Notebook panel or from the inline popover in the document.
| Action | Location | Result |
|---|---|---|
| Change Color | Notebook panel or inline popover | Replaces the current highlighter with the selected one |
Highlight text cannot be edited after creation. To correct a selection, delete the highlight and create a new one.
Converting a Highlight to a Note
Adding annotation text to a highlight converts it to a note. There is no separate "note" object in our reader model: a note is a highlight with a non-empty annotationText field. See Notes for the full flow.
Deleting a Highlight
Deleting a highlight is permanent. The action is available from the annotation's context menu in the Notebook panel or from the inline popover.
Deleted highlights cannot be recovered. Deleting a highlight that has annotation text also removes the associated note.
Sync and Persistence
| Context | Behavior |
|---|---|
| Authenticated (web or app) | Persisted to the backend in real time via the host bridge |
| Standalone mode (no host bridge) | Stored in localStorage; data is tied to the browser session |
| Offline | Changes are saved locally and synced when the connection is restored (last-write-wins conflict resolution) |
There is no explicit limit on the number of highlights a reader can create.
Related Documentation
- Notebook Overview - the full Notebook panel, tabs, export, and available actions
- Notes - highlights with annotation text added
- Highlighters - the color system and Quick Highlight mode configuration