File Extension PDF
File extension PDF is most commonly associated with Adobe
PDF files can be opened by Adobe Acrobat Reader application that can be downloaded from official Adobe website free of charge. This application is safe to use and doesn't contain any adware. There are several paid and free software packages that can view and edit PDF files.
Although Adobe Portalble Document Format files dominate file extension PDF there is a slight chance that PDF files contain some other data. Easiest way to check is to open PDF file in notepad. It should begin with %PDF-1. followed by a number which denotes version of PDF standard used in the file.