OCR stands for Optical Character Recognition, which enables images or printed text to be translated into machine-readable text. OCR must be used when scanning paper documents to create electronic copies, but can also be performed on existing electronic documents (e.g. PDF). In order to edit the scanned PDF files or image-based PDF files directly or convert them to the editable other format files (such as Word, Excel, PowerPoint, etc.) you need to perform OCR first before editing or converting it.