Computer :: science

ComputerAbout two hundred years before, the word computer started to appear in the dictionary. Some people in time didnt know what is a computer. However, most of the people today not just knowing what is a computer, but understand how to use a computer. Therefore, computer accommodate more and more popular and important to our society. We can use computer everywhere and they are very useful and helpful to our life. The speed and accuracy of computer made people felt confident and reliable. Therefore, many important information or data are saved in the computer. Such as your diary, the m unitarytary situation of a oil company or some secret intelligence of the military department. A lot of important information can be found in the memory of computer. So, people may ask a question Can we make sure that the information in the computer is harmless and nobody can steal it from the memory of the computer? Physical hazard is one of the causes of destroying the data in the computer. Fo r example, send a flood of coffee toward a personal computer. The hard disk of the computer could be endangered by the flood of coffee. Besides, human caretaker of computer system can cause as frequently as harm as any physical hazard. For example, a cashier in a bank can transfer some money from one of his customers account to his own account. Nonetheless, the most risky thief are not those who work with computer every day, but youthful amateurs who experiment at wickedness --- the hackers. The term hacker may have originated at M.I.T. as students jargon for classmates who labored nights in the computer lab. In the beginning, hackers are not so dangerous at all. They just stole computer time from the university. However, in the early 1980s, hackers became a group of criminals who steal information from other peoples computer. For preventing the hackers and other criminals, people impoverishment to set up a good security system to protect the data in the computer. The most import ant thing is that we cannot allow those hackers and criminals entering our computers. It intend that we need to design a lock to lock up all our data or using identification to verify the identity of someone want access to our computers. The most common method to lock up the data is using a password system. Passwords are a multi-user computer systems usual first off line of defense against hackers.