WARNING: You shouldn't enter your key on the Adobe website, just enter it during the installation process.
There are several options for reading and editing PDF documents nowadays but Adobe Acrobat Pro was the first. This Professional version of the software gives you the power to create, read and modify PDF documents.
Adobe Acrobat Pro DC gives you several different views to read PDF documents including different degrees of zoom. Most importantly, it allows you to edit documents, comment on them, add stamps, watermarks, and signatures as well as export them to a variety of formats including HTML and Postscript.
You can create PDFs from a variety of sources, including files, scanned documents and web pages. You can also combine and merge documents, create a PDF portfolio and use a variety of tools to add multimedia, create PDF forms, add digital signatures and much more.
A big plus of Adobe Acrobat Pro is that it also supports OCR scanning of documents. This means you can scan a document into your PC and Adobe Acrobat X will turn it into text you can edit. The accuracy and speed of this feature is impressive and eliminates the need for a third party OCR software. The big downside remains that Adobe Acrobat Pro DC can be painfully slow at starting and the installation process is a bit lengthy.
Adobe Acrobat Pro offers all the tools you'll ever need to manage and edit PDF documents.