Apple adds features and capabilities to each new version of Macintosh OS X. These additions often come in the form of improvements made to the built-in apps (e.g., Mail) and utilities (e.g., Finder). As a result, you might not even be aware of the enhancements.

Here are four useful tasks that you can perform in OS X Yosemite and OS X El Capitan that might come as a surprise to you:

1. Sign PDF Files in Mail

If you receive an email that includes a PDF file you need to sign, you can sign it right in Mail using the Markup tool. This saves you from having to print the file, sign it, and then scan the signed file so it is back in digital form.

To electronically sign a PDF document in Mail, follow these steps:

  1. Create a new email and attach the PDF file you need to sign.
  2. Hover your cursor over the file until you see a triangle icon appear and then click it.
  3. Choose “Markup”.
  4. Select the icon that looks like a signature.
  5. Choose “Create Signature”.
  6. Capture your signature using your computer’s trackpad or camera. To use the former, click the “Trackpad” option, select “Click Here to Begin”, create your signature on the trackpad, and click “Done”. To use the latter, sign a piece of white paper, choose “Camera”, hold the signature in front of your camera, and click “Done” once your signature appears in the window.
  7. Click the signature you just created to insert it into the PDF document. You can move or resize it as needed.
  8. Choose “Done” in the Markup tool.

2. Rename a Group of Files Simultaneously in Finder

In Finder, you can rename a group of files at the same time. Your options include replacing text within the filenames and adding text to the beginning or the end of them. You can even replace the original filenames with completely new ones that follow a specified format (e.g., custom name with a numbered sequence). After you tell Finder how to rename the files, it does the rest.

Here is how to use this feature:

  1. Select the files you want to rename in Finder.
  2. Control-click the selected items.
  3. Choose the “Rename” option.
  4. Select the “Replace Text”, “Add Text”, or “Format” option.
  5. Specify how you want to change the filenames.

3. Edit Images in Preview

Preview includes basic image-editing capabilities. For example, you can crop, resize, and add text to images. You can also adjust the colors (e.g., change the contrast or saturation level).

To use Preview’s image-editing capabilities, follow these steps:

  1. Open the image you want to edit in Preview.
  2. Bring up the editing toolbar by clicking the edit button (the button displaying either a toolbox or a pencil on a piece of paper).
  3. Adjust the image using the editing tools. For example, if you want to add text to an image, click the “Aa” icon, put your cursor where you want to place the text, and type it.

4. Use Spotlight for Measurement and Currency Conversions

Besides using Spotlight for searches, you can use it for measurement and currency conversions. For example, you can convert gallons to pints, miles per hour (mph) to kilometers per hour (kph), and U.S. dollars to Japanese yen.

Follow these steps to take advantage of Spotlight’s conversion functionality:

  1. Open Spotlight by clicking the magnifying glass in the upper right corner of your desktop.
  2. Type what you want to convert (e.g., 10 gallons, 65 mph, $1,000) in the search box.
  3. Look in the Quick Look pane for the results. Multiple results are usually displayed. For example, if you typed 10 gallons in the search box, the Quick Look pane will display the conversion to cubic feet (1.34), liters (37.85), quarts (40), pints (80), and cups (160).