1. .txt 2. .rtf. 3. .doc 4. .write
A WordPad document is a file.
If your file opens in another program you can right click your file and choose open with. Choose WordPad and make it default if you wish. If the file wont open in WordPad at all it's most likely a file-type not supported by WordPad. You might need additional software or convert the file to a supported type.
.edb file and .stm file
Rules for file extensions are based mainly on the underlying operating system and/or file system. Generally speaking, file extensions are just a part of the file name, and can be set to whatever you like.
.msc
It is a program. It is a very simple word processing application program.
magic
No, folders usually do not have file extensions, but they could have if you like. Usually only files have extensions, to indicate the contents of the file.
For windows, you might use .cmd, .bat as common file extensions. Unix doesn't use file extensions as associations, so no file extension needs to be used in the Unix environment. A shell script in Unix is simply a text file with any name that is readable and executable. However, file extensions are typically used in Unix as a documentation aid that states that the file is a shell script. Common extensions are .sh, .csh, .ksh, .tcsh, .zsh, etc.
You need to convert it. Formats need to be converted to change between file name extensions.
There are hundreds of filename extensions in use, and the set is constantly changing. The extensions are the characters after the period in dotted-name filename systems. They identify file types and serve to associate each with the application software that can properly interpret them. Please see the accompanying links for two Web sites that list file extensions.
Extensions are the last part of a file name for example a text file is usually called example.txt the .txt at the end is the extension and can be many differant things depending on the program that creats it.