You're probably reading this on one of your multiple devices.
I've noticed that Firefox and Chrome browsers on my phone and laptop allowed you to send a webpage's url to each other. So when you're browsing a webpage on your phone, you can send it to your laptop, and it will automatically open a new tab. This is only possible if you are signed into a Firefox account or a Google account on both devices. Historically, I've solved this problem with Pushbullet which allows you to use your phone's share button to send links, text, or files between a phone and a desktop's web browser via a plugin. It's a convinient service, also offering phone notification mirroring to your phone. Again, you must be logged into a pushbullet account on both devices.
If my phone and laptop are sitting next to each other on the table, why is it so difficult to get files between them? Lets look at some options:
Cloud Services (Google Drive, Dropbox):