Apple periodically releases updates and patches that will protect Mac OS X from being attacked by viruses and other malicious programs. Configuring OS X to automatically install these patches will ensure your computer is always protected.
1. Click on the Apple menu, and choose System Preferences.
2. In the window that appears, select Software Updates from the System section.
3. Check the box by Check for Updates and select Weekly from the pull–down menu.
4. Check the box by Download important updates in the background.