Why do Windows Files Have Percent Signs? 

Windows uses percent symbols in file paths to show that a text is an environment variable that stores file path information.
The environment variables in file paths makes it easier to access your files, and they allow programmers to be more flexible.
They make it easier to access your files because you don't have to type the entire file path, which can be quite long at times. For instance, to get to the temp folder, you can simply type %temp% as a Run command or from the file explorer.
Environment variables in file paths allow programmers to be more versatile, because they enable them to work with different system configurations. For example, in extremely rare cases the drive letter of Windows might not be the C: drive. This can be problematic, since many apps point to the C: drive by default. But, using the environment variable %systemdrive% will work even if Windows is not installed on the C: drive.
Of course, environment variables have other uses in Windows and in programming in general. They aren't only used to store file path information.
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