Oracle releases a patch bundle on a quarterly basis known as a Critical Patch Updates(CPU). It is strongly advised to install this patch as this provides security fixes on a regular basis. The CPUs are released every January, April, July, and October. For further information about CPU releases, you can refer to the information provided on the Critical Patch Updates and Security Alerts page located at http://www.oracle.com/technology/deploy/security/alerts.htm.

The procedure to install the CPU is detailed in the companion README.txt or README.html file which describes the steps required to install the CPU in detail. You must read this file prior to starting the apply session. The key tool to perform the CPU install is OPatch and the specific options required to perform this task may vary from CPU to CPU, so you must read the instructions included in the CPU.

CPUs are cumulative, so you don't have to apply all the CPUs for a given release. If you apply the latest CPU...