Many people are annoyed because of frequent Mac system crash. After the crash there is a possibility that the system may reboot or not. This can be because of any one application of the whole Operating system has been damaged. If the system reboots you should may see a message that an application quit unexpectedly and you can reopen the application. You can try and test by reopening it whether Mac system crash occurred due to it or not. If the system crashed you may have to reinstall the application. Another reason can be that there is any problem with the hardware, mainly in the hard drive of the Mac. The hard disk may have some file system issues or the file in it are affected by virus. Whatever the reason may be the Mac system crash will lead to data loss. The data can be very crucial for your business or office so you have to recover it quickly. After the system reboots successfully you may try to restore your data by using any personal back up. There is also Time Machine back up utility installed in Mac that restore data but you can not fully rely on it. It the back up fails then you can certainly use Mac data recovery software to recover data lost due to Mac system crash.