but why you write %Appdata%
Because it's the CORRECT way to express the roaming folder without doing something as cumbersome as:
C:\users\YOURNAME\Appdata\Roaming
And then having to explain that:
- YOURNAME is really your Windows login username
- if you installed Windows on some other driver the drive letter might not be C:
- on some Windows version the roaming folder might not even be under C:\Users.
Instead, just typing %APPDATA% will always find that folder, regardless how your login is, which drive your Windows or your user profile is set to, and with every version of Windows, that's why I always use this form.