How to Work with PDF Files: Reading, Filling and Sharing

The PDF format keeps a document's layout the same on every device, which is why it is used for forms, contracts and reports. Both Windows and Mac can open PDFs without extra software. This guide covers the everyday tasks people need: reading, signing, filling in forms, and making files smaller.

Open and read PDFs

Double-click a PDF to open it in your default viewer. Microsoft Edge and Chrome can also open PDFs in a browser tab. On Mac, Preview is built in and has basic tools for markup and page editing.

Fill in forms

If the form has fillable boxes, click in each field and type. If it does not, use the Text or Fill and Sign tool in your viewer to add text. Save a copy with a new name so the original stays blank.

Sign a document

Preview on Mac and most PDF readers let you draw a signature with a trackpad or add a picture of your signature. Use an electronic signature only when the other party accepts it, and check whether the document needs a formal digital signature instead.

Merge and split files

Mac: open the Preview sidebar, select pages, and drag them into another file. Choose File, then Export to save as a PDF.
Windows: many PDF editors and browser-based tools can merge files. Check the tool's privacy policy before uploading sensitive documents.

Make a PDF smaller

Large scanned PDFs can be hard to send by email. Use Export or Save As with a lower-quality setting, or use the Reduce File Size option in Preview. Check that the text is still readable after reducing the size.

Save a PDF from other files

To turn a Word document into a PDF, choose File, then Save As or Export, and select PDF. On Windows, the Microsoft Print to PDF option works from any app's print dialog.

Keep sensitive files safe

Do not send PDFs with personal data over unencrypted email if you can avoid it. Remove hidden personal information such as author names if needed, and be careful when using online converters.

Frequently asked questions

Why will my PDF not let me type?

The file may be locked by the author, or it may be a scanned image without fillable fields. Ask for an editable version or use a tool that adds text.

Are PDFs safe to open?

Generally yes, but PDFs can contain links to malicious sites. Do not click links or enable macros from files you do not trust.

Make PDFs accessible and searchable

A scanned PDF is an image, so the text cannot be searched or copied. Many tools can run optical character recognition (OCR) to add a text layer. Check the result carefully, because OCR can misread numbers and names. Save the text version as a new file and keep the original scan for reference.

Compare file sizes before sending

A PDF that is too large for email can often be sent through a file-sharing link instead. Compare the file size before you choose a method, and check whether the recipient needs to edit the file or only read it. Sending the right format saves time for both of you.