Online Clipboard
Copy text from your phone to your computer
An address, a phone number, a tracking link. It is on the phone and you need it on the computer, and typing it over is not an option.
The built-in options, and where they stop
On Apple devices, Universal Clipboard handles this: copy on the iPhone, paste on the Mac. It needs both devices signed in to the same Apple account, with Bluetooth and Wi-Fi on and the two nearby. It does not reach a Windows PC.
On Windows with an Android phone, clipboard sync through a Microsoft account works, as does Phone Link. Both need an account on both ends and a one-time setup. Neither helps with an iPhone.
Android to Android has Nearby Share, which is quick for files but less direct for a snippet of text.
Sending it to yourself
Emailing or messaging yourself always works, which is why so many people do it. The cost is that it takes four steps, needs an account on both ends, and leaves a trail in an inbox you then have to clean up. Messengers also recompress photos, which matters if the thing you are moving is a screenshot someone needs to read.
When the two devices do not match
This is the case the built-in features were never designed for: an iPhone next to a Windows PC, an Android phone next to a MacBook, a personal phone next to a locked-down work laptop where you cannot install anything and would rather not sign in.
A clipboard that lives on the web sidesteps the problem, because the only thing both devices need is a browser. Open Online Clipboard on the computer, scan the QR code with the phone, and the two share a board. Paste the text on the phone and it appears on the computer straight away; one click on the copy icon puts it into the system clipboard so you can paste it wherever you were going.
Nothing is installed, no account is created, and the entry deletes itself after seven days.
In short: If both devices belong to the same ecosystem, use the built-in feature. If they do not, a web-based clipboard is the shortest path that needs no account and no install.