Linux Kernel in a Nutshell

Name

MODULES — Enable loadable module support

Kernel modules are small pieces of compiled code that can be inserted in the running kernel, rather than being permanently built into the kernel. If you select this option, many parts of the kernel can be built as modules (by answering M instead of Y where indicated): this is most useful for infrequently used options that are not required for booting. For more information, see Chapter 4 and the manpages for modprobe, lsmod, modinfo, insmod, and rmmod.

If you say yes here, you will need to run make modules_install to put the modules under /lib/modules where the module tools can find them.