Password Pad is a text editor that many professionals use to secure their documents. The way the program works is actually pretty simple: you can simply lock up your documents with a password that only you know so that nobody else can access that report on your work computer, the Christmas shopping list that your kids might try and snoop at, or anything else that you want to keep private.
You will certainly want to look into Password Pad around tax time. If you're keeping a lot of personal financial information on your laptop, you never know who might try and peek, so password protecting those files only makes sense. PWDP - Password Pad Document is the way that the software stores information.
Right now, Password Pad is only available in the Mac download store, so if you're using Windows, then you may want to look into some PC-based equivalent of Password Pad. For Mac users, though, you're not likely to find a better and more versatile program to protect your files on your computer. Give it a try and see if you don't find it to be versatile, user friendly and most of all, incredibly secure and reliable.