Information Storage: Data and programs are stored primarily on magnetic media (floppy disks and hard disks). The disadvantage of magnetic media is that disks can be easily damaged by dust, the oils on your fingers, static electricity, magnets and many other seemingly innocuous things. They are not generally damaged by airport x-ray machines for the same reasons that most kinds of film are safe. The advantage of digital information storage however, is that you can easily and cheaply make many identical copies.
Data Backups: Floppy disks fail often. It is estimated that one disk in ten is imperfect from the factory and all disks are more prone to fail with age. Hard disks are more reliable but it is disastrous when they do fail since they store so much more information. Eventually you will lose some data. It is inevitable. Hopefully it won't be the Ph.D. thesis or hit novel you've been working on for years, though I know people who have lost such things. Apparently the U.S. government lost all census data for a particular year in the 1970's because the computer disks got corrupted and there was no paper backup. Take my advice. Save your work often, and keep back-ups of important files in several locations. Recent copies of my grades files are on a floppy disk, on paper in a locked file cabinet, and on three different computers (with password protection). A good rule is to save at least every half hour and back up at least once a month or whenever you make major changes. For mass backups, people use a variety of devices such as magnetic tapes, portable hard disks, magneto-optical disks, syquest cartridges, writeable CD-ROMs, hundreds of floppies (better them than me!) and zip drives. Retrospect is a great program that automates data backup.
Data Recovery: It is usually difficult to retrieve information from a damaged disk. However, there are several programs on the market for recovering files that have been damaged or accidentally deleted. They don't always work, but it's often worth a try. A popular cross-platform commercial program for disk repair is Norton Utilities.
Related Reading: Mac Troubleshooting, PC Troubleshooting
Virus Protection: Computer viruses are not a very common problem, but they tend to spread rapidly and wreak havoc when they are encountered. There are entire books written on the subject, which is fascinating in a twisted sort of way. I use two free programs called "Disinfectant" and "Gatekeeper" to keep our network clean. If you want these programs for your Macintosh, it is legal to copy them and pass them along in the interest of keeping the computer world virus free. Read the help information within the Disinfectant program to learn a great deal more about viruses.
Related Reading: Anti-Virus Info
Write Protection: A disk can be "locked" so that the computer can read information from it but not write (save) information to it. Such a disk is said to be "write protected". Write protected disks cannot be infected by a virus. New software usually comes on write protected floppies so it won't be accidentally erased. It is ok to write-protect program disks as long as you can save your data to another location. You can lock your disk by sliding the little tab in the top right corner.
Copy Protection: Disks, programs, and files are sometimes "locked" so they cannot be copied. This is done for a variety of reasons ranging from infringement of copyright to the protection of sensitive data. Of course, as with most arms races, every time a new copy protection scheme is invented, someone figures out a way to break it before too long. Most Macintosh programs are no longer copy protected, but many have registration information which gets encoded on the program disk the first time it is installed. If these programs get passed around, prosecutors then have a trail to follow back to the owner.
Software Piracy: Fines for software piracy are very large but, like copying music and taping movies off the air, many people ignore the law and get away with it. The people most likely to get caught are those in the business of illegal mass duplication and sale of software. However, there are lots of good reasons for individuals not to pirate software. (1) The most innovative software companies are firms with under a dozen employees that exist on razor thin profit margins. Software piracy kills these small creative companies and leaves us with only the giant software conglomerates that threaten to monopolize the entire industry. (2) If you buy your software you get instruction manuals. If you register, you get technical support, bug notifications, software patches, and upgrade offers. (3) A portion of the money a software company earns goes back into research and development. If you want companies to improve their software and to produce new titles, you've got to support them.
Related Reading: Software & Information Industry Association
Shareware and Freeware: Hobbyists, educators, and small companies offer programs to the public at little or no cost in order to further some charitable cause or to gain recognition in the industry. In some cases you can pass on copies for free, while in others, a small fee or a postcard to the author is all that they ask. Read the help or information screen for the particulars.
Related reading: Shareware Archives, Mac Shareware, Windows Shareware
Password Protection: A type of data security where a password must be entered by the owner of the file in order to gain access. If you forget the password however, you may lose access to your own file! Some passwords are "case sensitive", meaning that UPPERCASE and lowercase letters must be entered exactly as they were when the password was created.
Encryption: New techniques allow for the encryption of data to prevent eavesdropping. The federal government is disturbed by this development because it will make current electronic surveillance methods obsolete. Currently most e-mail systems are not secure. There was a recent case in the courts which upheld an employer's right to read an employee's e-mail without the employee's knowledge. (The employee was fired over what he said in the note.) Take a look at PGP's (Pretty Good Privacy) website.
Anti-Tamper Software: Some programs are designed to limit a user's ability to make modifications to a computer's pre-chosen settings. FoolProof prevents students from adding or removing programs or changing hard disk settings, while allowing them to use the programs normally and save to a floppy disk.