What can be edited with PDF files

Some PDF files can be edited, while encrypted protected PDF files can not be edited, and some PDF files are scanned by the form of PDF files, the content of this PDF file is actually scanned to form a picture, so it is not editable. In general, we directly double-click Open PDF files are the default PDF reader open, PDF reader does not have the editing function, so some people think the PDF file can not be edited.

Editing a PDF file is modified by a PDF editing Tool, so editing the PDF is done by opening the PDF file with the editor.
The text content of the PDF is manipulated in a text edit box. Each text box is relatively independent, and the position of the text can be adjusted by adjusting the position and size of the text box.
For pictures can be directly copied and pasted operations, position size can also be freely adjusted. You can set the order in which objects are displayed before and after each object by adjusting the object's sort.
Although each object can adjust its position arbitrarily, if the page display area is exceeded, the portion of the document is not displayed when viewed with a PDF reader.
The page Thumbnail window allows you to add or delete pages anywhere in the document. You can also adjust the order of the pages by dragging the page thumbnails.
Editing a completed document requires the selection of the output as PDF, and the file is saved in PDF format.
PDF How to edit http://jingyan.baidu.com/article/e75aca8567c264142fdac67b.html

What can be edited with PDF files