The symbol (\) used as a separator between folder and file names in Windows.  For example, 
c:\"program files"\CLC\CDEweb.exe is the "path" to the executable file in the CLC folder within the Program Files folder on the C: drive.  See 
path.
The choice of backslash is regrettable because the forward slash (/) is commonly used in the Linux, Unix and Mac worlds as well as all Internet addresses.  Windows developers must use both symbols.
Why?
Windows followed DOS, which was designed to compete with CP/M, the major personal computer operating system before the IBM PC reset everything.  CP/M used the forward slash, but to appear new and different, the backslash was chosen for DOS.
Double Backslashes (\\)
Two backslashes are used as a prefix to a server name (hostname) on the local network.  For example, 
\\server2\c\expenses is the path to the EXPENSES folder on the C: drive on server 2.  See 
UNC, 
\ and 
forward slash.
 Platform     Path to Ovens Folder
 Windows:     \products\kitchen\ovens
 macOS,
 Unix/Linux:  /products/kitchen/ovens
              Path to Ovens Page
 Internet:    greatproducts.com/kitchen/ovens
Three Symbols Separate Names
The Unix-based Mac uses the forward slash, while Windows uses the backslash.  Starting with Windows Vista, the Explorer path uses right arrows; however, backslashes must still be used at the command line (see 
cmd abc's).