. Whilst you're obviously going to do your best to keep your flash drive safe, the things are so small that they are quite easy to lose. Maybe lost down the back of the sofa with all that spare change or maybe put somewhere safe that is so safe you can't remember where it was.
If your USB isn't protected by a password, anyone can view the files on your missing pen drive.
If the files are simply innocuous pictures of landscapes that you took on holiday, you likely don't care. But if they're more precious - either for the memories they contain or the data that's in them - then chances are that you should use some kind of password protection to keep them safe.
The easiest way of protecting the files on your USB drive is with a password. There are various pieces of software out there that will do this for you and with these the main choice you have to make is whether to protect the whole USB flash drive or folders within it or even individual files.
The software that you choose should make it as easy as possible to "get it right" and should be intuitive to use. Otherwise if the software is too complicated then there's a very high chance that you won't use it and you'll be back to square one. So if you get a chance to use a trial version of the USB protection software, it's a good idea to run a test to see how well you get on with the software.