The two document formats lawyers most often encounter are Word (.docx) and Adobe Acrobat (.pdf). In Word 2013, you can not only open, create, and edit Word files, you can do the same with PDF documents.
For many years (since Word 2007), you have been able to save (or export) MS Word documents as PDF files from within Word. With Word 2013 (or Office 365, which includes Word 2013), you can open PDF files in Word. That process actually converts text-based PDF files into editable Word files. You can then make changes and save the modified document as a Word file and/or convert it back to PDF from within Word. This is a huge convenience. The downside is that the "round trip" conversion process from PDF to Word to PDF (like all similar "round trip" file format conversions) may cause the appearance of the document to change slightly. For example, page breaks or other formatting features may change from the original PDF.
If minor formatting changes are not a problem for you, here are the steps to open a PDF document in Word for editing:
In Word, browse to the PDF file you want to open. Then open it like you would any other document.
Click File > Open.
Choose the location of the PDF and click Browse.
Find the PDF and click Open.
When you are done editing the file, you can convert it back to PDF:
After editing the file, you can save the file as a Word document or as a PDF file. Your choice isn’t right or wrong; it will depend on how you intend to use the edited file. I recommend that you save the edited file as a Word document, even if you intend to distribute the file as a PDF.
When you save the file, Word will default to its format (.docx), so you need to take an extra step to save it to PDF:
Click the File tab and choose Save As.
Choose a location for the new file.
When Word displays the Save As dialog, you’ll notice that it has default to its native Word format.
From the Save As Type drop-down, choose PDF.
Usually it is better to first save the edited document to Word (.docx) format first, then re-save it to PDF. This two-step process seems to result in better conversions back to PDF.