In recent years, disk space has become outrageously cheap and abundant, but network bandwidth has not. Therefore, the Subversion working copy has been optimized around the scarcer resource.
The .svn administrative directory
      serves the same purpose as the CVS
      directory, except that it also stores read-only,
      “pristine” copies of your files.  This allows you
      to do many things offline:
Shows you any local changes you've made (see the section called “See an overview of your changes”)
Shows you the details of your changes (see the section called “Examine the details of your local modifications”)
Removes your local changes (see the section called “Undoing Working Changes”)
Also, the cached pristine files allow the Subversion client to send differences when committing, which CVS cannot do.
The last subcommand in the list—svn
      revert—is new.  It will not only remove local
      changes, but also unschedule operations such as adds and
      deletes.  Although deleting the file and then running svn
      update will still work, doing so distorts the true
      purpose of updating.  And, while we're on this subject…