We work with a general concept of files. Most programs read from the input and print to the output. Moreover, the input and the output is in fact text, so these are not files on their own. Because of this, everything is treated as a file. The folders are also files.
You can identify the following type of files:
Regular File
Directory (Folder)
Special device files are two types: character and Block devices
Hard Links
Symbolic Link
Sockets (this will resolve the network connection)
FIFO or named pipe
In the name of the files, any character may be present, excluding two. These are the / and the (the null character at the end of the string). Nevertheless, it is not recommended to use special characters inside the file names, as this can complicate working with them. Small and capital letters count, and you can also use the numbers and the - _ . characters.
The length of a file name inside modern operating systems can be up to 255 characters.
