Copies files and directories in a more advanced way than COPY, deprecated in Windows Vista and later in favor of ROBOCOPY.
Copies all files, but not files in nested folders, from the source folder ("C:\Windows\system") to the current folder.
xcopy /s /i C:\\Windows\\system C:\\Windows-2\\system
Copies all files and folders to any nesting depth (via "/s") from the source folder ("C:\Windows\system") to "C:\Windows-2\system", creating "Windows-2\system" if it does not exist (via "/i").
xcopy /s /i /d:09-01-2014 C:\\Windows\\system C:\\Windows-2\\system
As above, but copies only files changed on 1 September 2014 or later. Notice the use of the month-first convention even if you are on a non-US locale of Windows.
xcopy /L /s /i /d:09-01-2014 C:\\Windows\\system C:\\Windows-2\\system
As above, but in a test mode via /L (list-only, output-only, display-only). Thus, does not do any actual copying, merely lists what would be copied.
xcopy /s /i C:\\Windows\\system\\*.dll C:\\Windows-2\\system
As one of the examples above, but copies only files ending in .dll, including those in nested folders.
$ xcopy /? Copies files and directory trees. XCOPY source [destination] [/A | /M] [/D[:date]] [/P] [/S [/E]] [/V] [/W] [/C] [/I] [/Q] [/F] [/L] [/G] [/H] [/R] [/T] [/U] [/K] [/N] [/O] [/X] [/Y] [/-Y] [/Z] [/B] [/J] [/EXCLUDE:file1[+file2][+file3]...] source Specifies the file(s) to copy. destination Specifies the location and/or name of new files. /A Copies only files with the archive attribute set, doesn't change the attribute. /M Copies only files with the archive attribute set, turns off the archive attribute. /D:m-d-y Copies files changed on or after the specified date. If no date is given, copies only those files whose source time is newer than the destination time. /EXCLUDE:file1[+file2][+file3]... Specifies a list of files containing strings. Each string should be in a separate line in the files. When any of the strings match any part of the absolute path of the file to be copied, that file will be excluded from being copied. For example, specifying a string like \\obj\\ or .obj will exclude all files underneath the directory obj or all files with the .obj extension respectively. /P Prompts you before creating each destination file. /S Copies directories and subdirectories except empty ones. /E Copies directories and subdirectories, including empty ones. Same as /S /E. May be used to modify /T. /V Verifies the size of each new file. /W Prompts you to press a key before copying. /C Continues copying even if errors occur. /I If destination does not exist and copying more than one file, assumes that destination must be a directory. /Q Does not display file names while copying. /F Displays full source and destination file names while copying. /L Displays files that would be copied. /G Allows the copying of encrypted files to destination that does not support encryption. /H Copies hidden and system files also. /R Overwrites read-only files. /T Creates directory structure, but does not copy files. Does not include empty directories or subdirectories. /T /E includes empty directories and subdirectories. /U Copies only files that already exist in destination. /K Copies attributes. Normal Xcopy will reset read-only attributes. /N Copies using the generated short names. /O Copies file ownership and ACL information. /X Copies file audit settings (implies /O). /Y Suppresses prompting to confirm you want to overwrite an existing destination file. /-Y Causes prompting to confirm you want to overwrite an existing destination file. /Z Copies networked files in restartable mode. /B Copies the Symbolic Link itself versus the target of the link. /J Copies using unbuffered I/O. Recommended for very large files. The switch /Y may be preset in the COPYCMD environment variable. This may be overridden with /-Y on the command line.