what is an pdf file?
The pdf file extension is document file type with the purpose of maintaining consistency in presentation regardless of the system being used to view it.
download pdf sample file
ffc.pdf example file is licensed CC0, Public Domain Dedication
pdf file extensions
pdf file extension name
Portable Document Format
pdf file type
secondary: text, image
pdf file structure
Pdf files generally contain one or more pages of formatted text and images. The formatting of the text, dimensions of the pages, and number of pages are determined by the person creating the document.
pdf format specification and identification
pdf files contain four pieces: header, body, xref table, and trailer. Each piece contains information that ensures pdf files maintain consistent presentation across devices and tools.
When changes are made to a pdf file, instead of recreating the header, body, xref table, and trailer, a new section "body changes" is added with a second xref and trailer. This additive process is continued until the file is saved as a new file.
pdf MIME type
pdf file signature hex
25 50 44 46
pdf ISO 8859-1
pdf magic number
25 50 44 46 [%PDF]
pdf file character encoding / charset