Generally, there are 2 types of PDF; they are searchable and image PDF. A searchable PDF allows one to search and edit freely, while an image PDF is a scanned document or PDF file created from images and cannot be searchable or editable. It would require a tool to convert a non-searchable PDF to a searchable or editable PDF.
Most conversion software use OCR (Optical Character Recognition) tool to ‘read’ characters before conversion. The greatest challenge with the OCR process is that it is rarely error-free. Errors in conversion may range from subtle font inconsistencies that are hardly noticeable to critical misspellings or distorted graphics. Also, handwriting or signature will almost never be accurately recognized as text. Therefore, if you need to convert your paper-based documents to editable formats, it is advisable to scan to an image format (image pdf for multi-page documents; JPEG, TIFF, PNG for single-page documents), and use a tool (free or paid) to convert to editable formats. At least you would have an image copy, which is the exact, unedited copy of your document, even if there are issues with the converted copy.
At Tecres Technologies, we can scan and convert your paper-based documents to Text (*.txt), UNICODE Text (*.txt), Rich Text Format (*.rtf), HTML 4.0 (*.htm), Microsoft Word Document (*.doc), WordPerfect Document (*.wpd), XML Document (*.xml), Microsoft Excel Spreadsheet (*.xls), Open eBook 1.0 Document (*.opf), JPEG Image (*.jpg), TIFF (*.tif), PNG Image (*.png), Window Bitmap (*.bmp), XML Paper Specification (*.xps).