What Is a Searchable PDF?
A scanned PDF is really just a series of photos of pages — the "text" you see is pixels, not characters, so you can't select or search it. Making it searchable adds an invisible layer of actual text underneath, positioned to match the image, without changing what the page looks like.
Why scanned PDFs aren't searchable by default
A scanner (or a phone camera app that outputs to PDF) produces an image, then wraps that image in a PDF container. There's no text data anywhere in the file — Ctrl+F finds nothing because there's nothing to find, even though the words are clearly visible to a human reading the page.
How the fix works
Optical Character Recognition (OCR) reads the image and figures out what characters are actually printed on it, along with their position. FileBench's Make Searchable tool then adds that recognized text as an invisible layer, positioned exactly over the corresponding words in the image — the visible page looks identical, but Ctrl+F, text selection, and copy-paste now work against the real recognized text underneath.
Language matters
OCR has to know which language(s) to look for. FileBench's Make Searchable tool supports English, Arabic, or both in the same document — picking the wrong language (or missing one, for a bilingual page) reduces accuracy since the OCR engine is looking for the wrong character shapes.
Does making a PDF searchable change how it looks?
No — the added text layer is invisible. Visually the page is identical to the original scan; only the underlying, selectable text is new.
Is a searchable PDF the same as an editable one?
Not quite — searchable means you can find and select/copy text. Editing the actual page content (as opposed to the invisible text layer) still isn't possible the way it would be in a Word document, since the visible page is still a fixed image.