You got a .rar file and you don't how to open it, some one asked you to send him "a rar file" or you just need a good archiving software? Download and install WinRAR.
Sometimes when you are writing a title, one last word jumps into the next row. If you don't want to change the font size, there is another way to deal with these so called widow words.
You are trying to install or open an app that didn't come from the Mac App Store but you got a message saying App can't be opened because it is from an unidentified developer. This is how you bypass it.
