Hi Ahmad,
When saving text files using Notepad, the default text encoding format is set to ANSI. On the other hand, if you open a text file on a computer that's using a different encoding, the computer displays whatever the character corresponds to. A character encoding is a system that pairs each character in a supported character set with some value that represents that character. Thus, selecting appropriate encoding format is considered before saving the file.
Let us know should you need further assistance.