If you want to update the kernel from new source code you have downloaded, or you have applied a patch to add new functionality or hardware support, you must compile and install a new kernel to actually use that new functionality. Compiling the kernel involves translating the kernel’s contents from human-readable code to binary form. Installing the kernel involves putting all the compiled files where they belong in
/lib and making changes to the boot loader.
The process of compiling the kernel is almost completely automated by the make utility like the process of installing. By providing the necessary arguments and following the steps covered next, you can recompile and install a custom kernel for your use.