Signing a document online takes about thirty seconds. Most people spend twenty minutes doing it, because they've inherited a habit that involves a printer, and printers are where documents go to die.
Here are the ways to sign something without paper, in order of how well they hold up.
Print, sign, scan: the one to stop doing
You print the document, sign it, then photograph it badly or feed it through a scanner, and email back a 4MB image of a slightly crooked page.
It works. It's also the weakest option on this list. The output is a picture, so nothing in the file records who signed or when, the text is no longer selectable, and you've spent real time and money to end up with less evidence than if you'd done nothing clever at all. If you're still doing this because it feels more official, it isn't.
Markup on your phone: fine for low-stakes
Every modern phone signs PDFs out of the box. On iPhone, open the file from Mail or Files, tap the markup pen, and add a signature you draw once and reuse. Android does the same through Google Drive or any PDF reader.
This is genuinely quick and it produces a proper PDF rather than a photo. Use it for the things that pass across your desk all day: a delivery note, a permission slip, an internal form, a document where nobody is ever going to dispute anything.
The limitation is that the signature is just a drawing sitting on top of the page. There's no record of who drew it. For anything you'd be upset to lose an argument about, that's not enough.
A stored signature image: convenient and easy to deny
At some point most people crop their signature out of an old scan and keep the PNG on their desktop, ready to drop into anything.
Convenient. Also the version a lawyer takes apart in about a sentence, because that file could have been placed on that page by anyone with access to your laptop, on any date, and the document itself can't say otherwise. Signing your own paperwork this way is a bit like keeping a rubber stamp of your signature on the reception desk.
Use it for internal things. Don't use it on contracts.
A signing link: what to use for anything real
You send the other party a link. They open the document, sign it in their browser, and it comes back to you as a finished PDF along with a record of the exchange.
The signature itself might look identical to the drawn one from option two. The difference is everything around it: the link went to a specific email address or phone number, it was opened at a specific time from a specific device, and the document was submitted in a specific state. That chain is the reason this option survives being questioned and the others don't.
It's also faster for the person signing, which matters more than it sounds. A client who has to download an attachment, find an app, sign, save and re-attach will get to it tomorrow. A client who taps a link on their phone signs before they've put the phone down.
The part everyone gets wrong
Whichever route you take, a signature is a signature on one specific version of a document. Not on the deal, not on the general understanding. On that page, as it read at that moment.
So if you change a figure and resend, the old signature is worthless. If you keep the signed PDF but let the editable original drift, you can no longer show what was agreed. And if you save only the final signed file and throw away the email trail, you've kept the mark and discarded the proof.
Keep the signed copy, the version that was signed, and the record of the exchange. All three.
E·BIZI Papers is built around that: design the document once, email a link, and the signed PDF comes back with the trail attached instead of arriving as a photograph of a crooked page.