- Acrobat User Guide
- Introduction to Acrobat
- Workspace
- Workspace basics
- Opening and viewing PDFs
- Working with online storage accounts
- Acrobat and macOS
- Acrobat notifications
- Grids, guides, and measurements in PDFs
- Asian, Cyrillic, and right-to-left text in PDFs
- Workspace basics
- Creating PDFs
- Editing PDFs
- Edit text in PDFs
- Edit images or objects in a PDF
- Rotate, move, delete, and renumber PDF pages
- Edit scanned PDFs
- Enhance document photos captured using a mobile camera
- Optimizing PDFs
- PDF properties and metadata
- Links and attachments in PDFs
- PDF layers
- Page thumbnails and bookmarks in PDFs
- PDFs converted to web pages
- Setting up PDFs for a presentation
- PDF articles
- Geospatial PDFs
- Applying actions and scripts to PDFs
- Change the default font for adding text
- Delete pages from a PDF
- Scan and OCR
- Forms
- PDF forms basics
- Create a form from scratch in Acrobat
- Create and distribute PDF forms
- Fill in PDF forms
- PDF form field properties
- Fill and sign PDF forms
- Setting action buttons in PDF forms
- Publishing interactive PDF web forms
- PDF form field basics
- PDF barcode form fields
- Collect and manage PDF form data
- About forms tracker
- PDF forms help
- Send PDF forms to recipients using email or an internal server
- Combining files
- Combine or merge files into single PDF
- Rotate, move, delete, and renumber PDF pages
- Add headers, footers, and Bates numbering to PDFs
- Crop PDF pages
- Add watermarks to PDFs
- Add backgrounds to PDFs
- Working with component files in a PDF Portfolio
- Publish and share PDF Portfolios
- Overview of PDF Portfolios
- Create and customize PDF Portfolios
- Sharing, reviews, and commenting
- Share and track PDFs online
- Mark up text with edits
- Preparing for a PDF review
- Starting a PDF review
- Hosting shared reviews on SharePoint or Office 365 sites
- Participating in a PDF review
- Add comments to PDFs
- Adding a stamp to a PDF
- Approval workflows
- Managing comments | view, reply, print
- Importing and exporting comments
- Tracking and managing PDF reviews
- Saving and exporting PDFs
- Security
- Enhanced security setting for PDFs
- Securing PDFs with passwords
- Manage Digital IDs
- Securing PDFs with certificates
- Opening secured PDFs
- Removing sensitive content from PDFs
- Setting up security policies for PDFs
- Choosing a security method for PDFs
- Security warnings when a PDF opens
- Securing PDFs with Adobe Experience Manager
- Protected View feature for PDFs
- Overview of security in Acrobat and PDFs
- JavaScripts in PDFs as a security risk
- Attachments as security risks
- Allow or block links in PDFs
- Electronic signatures
- Sign PDF documents
- Capture your signature on mobile and use it everywhere
- Send documents for e-signatures
- Create a web form
- Request e-signatures in bulk
- Collect online payments
- Brand your account
- About certificate signatures
- Certificate-based signatures
- Validating digital signatures
- Adobe Approved Trust List
- Manage trusted identities
- Printing
- Accessibility, tags, and reflow
- Searching and indexing
- Multimedia and 3D models
- Add audio, video, and interactive objects to PDFs
- Adding 3D models to PDFs (Acrobat Pro)
- Displaying 3D models in PDFs
- Interacting with 3D models
- Measuring 3D objects in PDFs
- Setting 3D views in PDFs
- Enable 3D content in PDF
- Adding multimedia to PDFs
- Commenting on 3D designs in PDFs
- Playing video, audio, and multimedia formats in PDFs
- Add comments to videos
- Print production tools (Acrobat Pro)
- Preflight (Acrobat Pro)
- PDF/X-, PDF/A-, and PDF/E-compliant files
- Preflight profiles
- Advanced preflight inspections
- Preflight reports
- Viewing preflight results, objects, and resources
- Output intents in PDFs
- Correcting problem areas with the Preflight tool
- Automating document analysis with droplets or preflight actions
- Analyzing documents with the Preflight tool
- Additional checks in the Preflight tool
- Preflight libraries
- Preflight variables
- Color management
You sometimes see a warning when you open a PDF. The warning comes in many forms (three are shown below).
What does the warning mean?
The warning is asking whether you trust the people who sent you the PDF or the site in which the PDF is displayed. The warning appears because the PDF content can potentially harm your computer. For example, the warning is displayed for PDFs that can transfer or run programs and macros. It does not necessarily mean that the PDF is harmful.
What is the right action to take?
Some product features assign trust through their own Preferences panel. For example, the Trust Manager includes for managing URL access, and Multimedia Trust (Legacy) has options for playing embedded multimedia. For features affected when enhanced security is enabled, you can selectively allow restricted actions by using a method described in Bypass enhanced security restrictions.
To open Preferences, choose Edit > Preferences (Windows) or Acrobat / Adobe Acrobat Reader > Preferences (Mac OS).
If you know and trust the sender
If you trust the PDF or the company or individual who sent it, click the Options, Allow, or Play button. (The buttons vary depending on the warning.) You can now view the PDF.
If you don’t know or trust the sender
If you don't trust the PDF or don't know who created it or where it came from, don't click the Options, Allow, or Play button. Acrobat and Adobe Acrobat Reader continues to block the suspicious content or actions. To hide the warning, click the Close or Cancel button. If you click any of the blocked content, the warning reappears.
No Options, Allow, or Play button?
If the warning does not contain an Options, Allow, or Play button, your administrator has disabled this feature. You cannot choose to trust or allow this content. Click the Close or Cancel button to hide the warning. You can view the PDF, but you cannot access any of the blocked content. Contact your administrator for more information.
For a full list of articles about security, see Overview of security in Acrobat and PDF content.
When are security warnings displayed?
Security warnings can be displayed in the following situations:
Blacklisted JavaScript
JavaScript is a computer language in widespread use. JavaScript code can be vulnerable to attacks, and JavaScript can be used to open websites. Adobe regularly updates the blacklist with known JavaScript vulnerabilities. If a PDF tries to access blacklisted JavaScript, you see a message in the yellow document bar, at the top.
For administrators:
For instructions on how to manage JavaScript execution, see the article JavaScripts in PDFs as a security risk
For more information about the situations that trigger JavaScript warnings and blacklisted JavaScript, see www.adobe.com/go/acroappsecurity.
Security settings updates
Adobe periodically distributes certificates for security purposes. These downloads help ensure that digitally signed PDFs from trusted sources maintain their trusted status. If you receive an update from an unknown source, verify that it is from a web address that you trust before proceeding. Updates from untrusted websites can create vulnerabilities on your computer.
Accessing stream objects (XObjects)
Acrobat and Reader display a warning when a PDF attempts to access external content identified as a stream object. For example, a URL might point to an external image. The silent transmission of data can pose a security risk as Acrobat and Reader communicate with an external source.
Inserting data into PDFs and forms
A warning appears when an untrusted source attempts to add data to a PDF form. Although this data-injection feature can streamline workflows in your organization, it can also be used to add malicious data into a PDF.
Silent printing
Silent printing is printing to a file or printer without your confirmation. It is a potential security risk because a malicious file can silently print multiple times to your printer, wasting printer resources. It can also prevent other documents from printing by keeping the printer busy.
Contact your system administrator to determine when to allow silent printing.
Web links
In addition to visible web links in a PDF document, form fields can contain hidden JavaScript that open a page in a browser or silently request data from the Internet.
Acrobat and Reader X, 9.3, and 8.2 enable enhanced security by default. Adobe recommends that you enable enhanced security if it is not already enabled, and bypass restrictions only for trusted content.