When you are reading a massive digital textbook or a highly dense legal contract on your Mac, you often need to draw attention to specific sentences so you can quickly find them later. You do not need to print the document or use expensive PDF management software to accomplish this. The built-in macOS Preview application contains a highly robust, dedicated markup engine that allows you to instantly highlight text in multiple colors, exactly like using a physical neon marker.
How to Access the Highlight Tool
The highlighting engine is one of the most prominent features in the Preview interface, completely separate from the deeper, vector-based drawing tools.
- Double-click your PDF document to open it in Preview.
- Look at the main toolbar at the absolute top of the window (next to the search bar).
- Click the Highlight icon (it looks like a thick marker pen with a line of color underneath it).
Once you click the icon, it will turn dark grey to indicate it is active. Your mouse cursor will change from a standard pointer into a text-selection I-beam.
How to Highlight Text
With the tool active, applying the neon color is incredibly intuitive.
Simply click and hold your mouse button at the beginning of a sentence, drag your cursor across the words you want to emphasize, and release the mouse button. The text will instantly be wrapped in a bright, semi-transparent background color (usually yellow by default).
Because Preview reads the underlying OCR text data of the PDF, the highlight will snap perfectly to the exact geometry of the font, ensuring clean, perfectly straight lines rather than messy, freehand scribbles.
How to Change Colors and Remove Highlights
If you are color-coding your research (e.g., using yellow for general notes and red for critical legal warnings), you must change the active marker color.
- Look at the Highlight icon on the top toolbar. Notice the small Down Arrow directly next to it.
- Click the Down Arrow to open the color palette drop-down menu.
- Select a new color (Yellow, Green, Blue, Pink, or Purple). You can also choose the “Underline” or “Strikethrough” options from this menu to change how the emphasis is applied.
If you accidentally highlighted the wrong paragraph and need to delete the color, you cannot use the eraser tool. Instead, simply click directly on the highlighted text. A small, floating menu will appear above the text. Click the small ‘X’ icon in this menu, or press the Delete key on your Mac keyboard, to instantly strip the color away and return the text to normal.