File compression reduces the amount of disk space that is required to store files and increases the amount of information that can be placed on a single volume. This is useful on a volume that is running low on available disk space. Windows XP Professional supports file compression on NTFS volumes only.
You can enable compression for an entire NTFS volume, for one or more folders, or for individual files. Each file and folder has its own compression attribute that you can control on an individual basis. Windows provides compression entirely through NTFS, and after a file or folder is compressed, that compression is transparent to applications and users. The NTFS compression filter automatically decompresses files into memory when you open them and compresses any files again when they are saved to the disk. To enable compression of a volume, folder, or file on an NTFS partition, follow these steps:
1. In Windows Explorer, right-click the volume, folder, or file that you want to compress and select the Properties option from the action menu.
2. In the Properties dialog box for the volume, folder, or file, on the General tab, click Advanced.
3. In the Advanced Attributes dialog box, select the Compress Contents To Save Disk Space option and click OK.
4. If you have selected a folder that contains files and subfolders, you will be prompted to apply compression—either to the folder only or to the files and subfolders, Select the appropriate response and click OK.