Most PDF readers search with Ctrl and F on Windows or Command and F on Mac. Smallpdf's guide suggests checking whether a sentence can be selected when search finds nothing. A visible page may be an image rather than actual text.

Illustrative image
Illustrative image.

Use OCR for an image-based scan when searchable content is required. Test the processed output instead of returning to the original file, and review important matches where recognition quality may be affected by the scan.