Imagine you want to edit a printed document like a book, a magazine article or a printed contract. You need to spend hours to type the document from the beginning and be careful about the mistakes. Or you can use an Optical Character Recognition (OCR) tool to scan the printed document and digitize the whole text.
OCR is a great solution for converting human-to-human communication but falls short when converting more structured documents such as forms that need to be processed by machines.
Human-to-human communication is mostly in the form of free text like the one you are reading now. Such documents are called unstructured data and while they are great for human-to-human communication but they are hard for machines to understand. OCR converts the text in unstructured data into machine readable text so it can be searched and therefore more easily consumed by humans.