securities of systems is essential for the privacy of the users. Every person who is using systems in office or home desires to have his/her privacy. For this reason, even if you do not have confidential data in your system, you need to have a security system in place. Of course you would not want your information to reach to wrong hands. This may include your passwords or other information which can be altered by others.
For that system security is desirable. The costs and benefits of security should be carefully examined in economic in terms to ensure that the cost of controls does not exceed expected benefits.   Security should be suitable and balanced to the value of and degree of reliance on the computer systems and to the harshness and extent of potential harm.  Requirements for security vary, depending upon the particular computer system.