I often hear them say that a software has a "dongle". What is a dongle? Is it an encryption lock?

I often hear them say that a software has a "dongle". What is a dongle? Is it an encryption lock?

Do you have to plug this thing when you want to use it, or what? Don't understand? The main reason is that I haven't used it, but I always listen to them say that I often use the U disk. Is it true that only genuine edition has this thing!

There are a lot of software have this thing

The appearance is the same as that of USB flash disk

Like UFIDA, housekeeper financial software most have this thing

For example: open a software, a software will pop up a verification window, at this time you have to insert the dongle (actually is the key), after inserting it can be used normally

Of course, only genuine version has a dongle. The most expensive one is the dongle after buying the software. Even if it's useless to crack the software, it can only be used by cracking the dongle. It's very high-tech