How to edit a PDF file
Foxit Reader is an alternative light and free Adobe Reader that a lot of peopleprefer. It displays PDF files very well and quickly and offers a wide range of powerful tools. You can not edit the content directly, but the text can be barred by one line and replaced by a pop-up note.
You can also insert notes, attach page files, add text boxes or captions, draw with a pencil, add rectangles, lines, arrows, polygons and clouds, or even add buffers like Approve, Rejection and so on. This is the tool Idale if you want comment and annotate PDF files.
PDF-XChange Viewer offers a set almost the same features that Foxit Reader and it is just as useful for annotating PDF files.
PDFCool Free Studio
Although it suffers from some BugsPDFCool Free Studio has some features helpful. he can extract the text and the images from a PDF, which later will allow to edit them in another software like Word for example. You can enter text on a page and have basic drawing functions to draw lines, circles, and rectangles. It is still not as good as Foxit Reader though.
LibreOffice is one of only solutions if you want to edit the text for free in a PDF file. It natively supports PDF files and even if it is very large documents with hundreds of pages.