Nowadays, CD and DVD are widely used to store different kinds of important data. If users want to protect data stored on CD or DVD, they should use and keep CD and DVD correctly. Well then, what should users notice when using and keeping CD and DVD? Firstly, users had better not use pirated CD and DVD, because quality of pirated disk can not be ensured. Secondly, do not touch the platter of optical disk so as to avoid scratch and contamination. Thirdly, do not take optical disk when there is dirt or oil contamination on the hand. If contamination is attached to optical disk, data read will be influenced. Fourthly, put CD or DVD to optical disk cartridge after use. Fifthly, do not press the button “Eject” optionally when optical disk is working. If the optical disk pups up when it spins at a high speed, platter is easy to damage. At last, lay optical disk vertically rather than horizontally and keep it o a place without high temperature, moist, great pressure, and direct sunlight. Actually, apart from aspects mentioned above, users should be cautious about personal operation if they want to further ensure CD/DVD data security. Both mistaken deletion and formatting may result in data loss. Since it is difficult to realize CD/DVD data recovery, use CD/DVD correctly, take appropriate measures to keep CD/DVD, and pay much attention to personal operation.