You try to select a paragraph and the cursor draws a box instead of highlighting words. Or the text highlights, you copy it, and what lands in your document is "" or similar nonsense. These look like the same problem and are not.
There are three distinct causes. Work out which one you have before trying fixes, because the fix for one does nothing for the others.
Cause one: the page is an image
Symptom: dragging across the text draws a selection rectangle, like selecting on a photo. Nothing highlights.
Why: the PDF contains no text at all. Someone scanned a document or photographed it, and what you are looking at is a picture of words. There is nothing to select because, as far as the file is concerned, there are no words.
Fix: OCR — optical character recognition — which examines the image and works out what the letters are. That is genuinely a different technology from text extraction, and our tools do not do it yet. Free options that do include Google Drive (upload the PDF, right-click, Open with Google Docs, which runs OCR automatically) and most modern scanner apps, which offer a "searchable PDF" option.
Once OCR has produced a text layer, extraction works normally.
Cause two: the text is there but copying is restricted
Symptom: text highlights normally when you drag across it, but Copy is greyed out, or pasting produces nothing.
Why: the PDF has owner restrictions — permission flags set by whoever produced it, saying content should not be extracted. Important detail: this is a *request*, not encryption. The text sits in the file unencrypted; viewers voluntarily honour the flag.
Fix: [PDF to Text](/pdf-to-text) reads the text layer directly rather than going through a viewer's copy function, so it is not affected by the permission flag. Same for [PDF to Word](/pdf-to-word) if you want it as an editable document.
Worth saying plainly: those flags are usually there for a reason. Extracting text from a document you have a right to read, to quote or reference it, is ordinary. Republishing someone's paid content is not, and the flag being trivial to bypass does not change that.
Cause three: the font encoding is broken
Symptom: text selects and copies fine, but what you paste is garbage — random symbols, boxes, or letters in the wrong order.
Why: this is the subtle one. A PDF font maps character codes to glyph shapes. If the producing software embedded a subset font without a proper "ToUnicode" map, the file knows how to *draw* each character but not what character it *is*. The page looks perfect and the underlying data is meaningless.
This is common with PDFs exported from older versions of LaTeX, some CAD packages, and certain corporate report generators.
Fix: there is no clean one, because the information genuinely is not in the file. Options in order of preference:
How to tell which one you have in five seconds
Press Ctrl+F (Cmd+F on Mac) in your PDF viewer and search for a word you can plainly see on the page.
That single test tells you which of the three problems you have and saves trying fixes that were never going to work.