After you have saved your changes to your local Web application and you are ready to propagate your changes to the master Web application, you can release the working copies.
To update the master Web application
Your local versions of the files are copied to the master Web server and become the current versions on the master Web application. If someone else has made changes to the master version since you got the copy you changed, the Merge dialog box appears and allows you to review differences and accept or reject the changes. For more information, see Resolving Merge Conflicts.
You might not want your changes propagated to the master Web server. For example, you may have decided you like the way the current version handled a scripting challenge better than the changes you just made to the local file. You can discard your current write-enabled copy, leaving the master version in tact.
To discard changes to a local copy
Your local copy of each selected file is replaced by the master version of the file.