A photo of a document and a scan of a document are different things: scans straighten the page, boost contrast so text pops, trim the table out of the picture, and save as a tidy PDF that offices, schools and banks accept happily. Your phone already does this properly — free.
iPhone: scan with the Notes app
1. Open Notes and start (or open) a note. 2. Tap the paperclip/attachment icon (or the camera icon) → Scan Documents. 3. Hold the phone over the page — in Auto mode it detects the edges and captures by itself; tap the shutter for manual. 4. Drag the corners if the frame is off, tap Keep Scan, add more pages the same way, then Save. 5. The scan lives in the note as a PDF. Share it via the Share button → Mail/WhatsApp/Files, and rename it something a human can file: Passport-Scan.pdf beats Scan 14.pdf.
iPhone bonus: scan straight into Files
In the Files app, open a folder, tap the … menu → Scan Documents. Same scanner, but the PDF lands directly in that folder — cleaner for ongoing paperwork.
Android: scan with Google Drive
1. Open Google Drive → tap + New → Scan (on some phones: the camera shortcut on the Drive home screen). 2. Frame the page and shoot; Drive auto-crops and straightens. 3. Adjust corners if needed, apply the clean-up filter (B&W usually reads best for text), add pages with the + button. 4. Save — name it properly — and it becomes a PDF in your Drive, shareable by link or attachment.
Many Android brands also include a scanner in the Camera or Notes app (Samsung Notes and Xiaomi's scanner are both good); the output and steps are nearly identical.
Tips for scans that get accepted
Scan on a dark, plain surface in bright, even light — watch for your own shadow across the page. Flatten curled pages under a book edge first. Keep the resolution at the default (more is not better — giant files annoy email). For ID cards, scan front and back into one PDF. And for anything sensitive, prefer sharing the PDF as an attachment over a link with broad access — then delete the cloud copy when it has served its purpose.
Signing a scanned document
On iPhone, open the scan → Markup → + → Add Signature lets you sign with a finger and place it. On Android, the Drive PDF viewer's annotate tools cover most needs. For anything legally weighty, a dedicated e-signature service adds audit trails; for school forms and office paperwork, phone markup is entirely standard practice now.