Copyright Goodheart-Willcox Co., Inc. Chapter 4 File Management 169 completely restore all data to a previous point that was working. This is usually done to correct a serious problem that causes the system to stop working. There are many third-party backup utilities available. Some are freeware and some are for-purchase software. Most backup programs can be scheduled to automatically run at periodic intervals established by the user. It is common to set a backup utility to run overnight when there is no user activity on the system. File Compression The amount of space a fi le takes up on the disk is not as great of a concern today as it was when disk drives were very limited in size. However, when sharing fi les, fi le size is a concern. Large fi les take longer to move across a network than small fi les. Many e-mail services limit the size of a fi le that can be attached to a message. Large fi les take up more space on an external drive and may quickly fi ll up the device. The solution is fi le compression. File compression is a process of compacting the data in a fi le or group of fi les to reduce the overall size. When a fi le is created by a software program, it is generally formatted so that reloading the fi le is quick and effi cient. As a result, the fi le may be larger than it needs to be. Some fi le-compression technologies eliminate repeated patterns in a fi le to reduce the overall size. There are other steps to take to compress a fi le, but the result is the same. The original content of the fi le is preserved, but the fi le is smaller. Computing Fundamentals 3.6.5, 5.1.4 Computing Fundamentals 3.4.1, 3.4.3 FYI FYI Some compressed fi le types, such as JPG, may be “lossy,” which means some of the original bits may be removed during compression. Click to create a system image Goodheart-Willcox Publisher Figure 4-16. The Windows Backup and Restore utility is used to back up files and create a system image. GS4 GS5