Which file format should I pick?

PDF for documents you are sending somewhere, such as a certificate or a form. JPEG for photographs. Many Swedish authorities and insurers accept only PDF, so choose that when you are unsure.

Can I scan without a printer?

Yes. A phone camera does the job well. On iPhone, Scan Documents lives in the Notes app; on Android, Scan sits in Google Drive. The result is a PDF with straight edges that authorities and banks accept.

Where does the scanned file end up?

On Windows it normally lands in the Pictures folder under Scanned Documents. On a Mac you choose the destination folder in the scanner window before pressing Scan. Scanning with a phone saves the PDF in the app you scanned from.

What resolution do I need?

300 dpi is enough for text and is the usual choice. Higher numbers make bigger files without making the text easier to read. For photos you plan to enlarge, 600 dpi can be worth it.

How to scan a document from your printer to a computer

Scanning means making a digital copy of a piece of paper, usually as a PDF file you can send on. Almost any printer with a lid and a glass plate can do it, and one page takes under a minute. If you have no printer, your phone camera does the same job.

Try this first

Lift the printer's lid and place the paper face down on the glass.
Line the corner of the paper up with the corner of the glass that has an arrow or a small mark. That keeps the image straight.
Close the lid. If the printer has a feeder on top, multi-page documents can go there instead, face up.
On Windows: press Start, type Scan and open Windows Fax and Scan. Choose your printer from the list, pick PDF or JPEG, choose colour or black and white and 300 dpi. Press Preview to check the page sits straight, then press Scan.
On a Mac: System Settings > Printers and Scanners. Select the printer, press Scanner and then Open Scanner. Choose the destination folder and the format, then press Scan.

Once it goes through, the file waits where you chose to save it, on Windows normally in Pictures under Scanned Documents.

If that did not help

If the printer is missing from the list, it is probably on a different wireless network than the computer. Check that both are on the same network name. Most printers can only use the one without 5G in the name.
Install the manufacturer's app and scan from there: HP Smart, Canon PRINT or Epson Smart Panel. They exist for both computers and phones and often find the printer when the built-in Windows tools do not.
If the image comes out crooked or dark, wipe the glass with a dry cloth, line the paper up with the corner mark and close the lid fully before scanning again.
Scan with your phone instead. On iPhone: open Notes, start a new note, tap the camera icon and choose Scan Documents. The phone finds the edges for you. Tap Save, then share the file as a PDF.
On Android: open Google Drive, tap the plus button and choose Scan. Take the picture, adjust the edges if needed and save. The result is a PDF.

A phone scan is really a photograph, so the light matters. Put the paper on a table with light coming from the side and hold the phone straight above it, and the text comes out sharp.

Before you send the document

If you are scanning something sensitive, such as a medical certificate, a power of attorney or a bank statement, keep the file on your own computer or phone rather than in a shared folder. Never send copies of bank cards, passwords or codes to anyone who asks for them, however the request arrives. A genuine authority, bank or insurer never asks for your codes, and neither do we.