Imagine, if you will, that you have a file – or a set of files – you want or need to share with someone. You can invite them to sit by your computer and stare at your screen. Easy, when they live with you under the same roof, or have just dropped by, even though, with laziness what it is these days, they might decline the invitation to climb a few stairs into your home office or den or wherever it is you keep your computer. Still, laziness has been quite correctly described as the mother of progress. So, to avoid the need to move their bums from one screen to another, people came up with computer networks. And, while they were at it, they figured out how to use this networking to share stuff between individual computers, no matter where they are.
The good thing is, you can decide which part of your computer will be open and which one will be off-limits to others. Basically, when someone on your network links to your computer, they will only see what you allow them to see.
And you can also decide what you allow others to do with your files: you can let them copy your files onto their machines and feel free to do whatever, but your original will remain safe, or you can allow them to make changes to files right there, on your computer. Be careful about the last-named gimmick, however, it can cost you. And, while you’re at file sharing, don’t forget to minimize the risks even more by making sure you’re using safe, encrypted connections.