A PDF is a versatile format. In addition to all the ways you can modify the file, you can also use it as a storage container. You can attach other files to it which can be extracted at a later time. 

• In the Comment tab, click the Attachment.

• Click anywhere on the document to see the Open dialog box. Choose your file and click Open to add this file.
• The attachment icon will appear on your page.
• To open your attachment, make sure you are in the View mode and click the attachment icon.

• To save an attached file to your computer, switch to the Edit mode, right-click the attachment icon, and choose Save Embedded File to Disk… in the context menu. 

• Alternatively, click the Extras panel icon on the right-hand side of the application window.
• Click the Paperclip icon to open the Attachments section.

• You can add any attachments by clicking on Add or Plus icon. This will open a Browse window allowing you to go through your computer looking for files to attach. 
  
  

• You can right-click on an attached file to Open, Save, or Delete it. 

• Click here to type a file description.

• Click the three dots to find the options Save all attachments and Delete all attachments.