ioctl - module or driver?

I am finally making progress using ioctl to access I2C device.
Among other resources I have been using A. Rubini's " Linux device drivers".

He describes ioctl function as "communicator module " - my interpretation.

I am under the impression that "modules" are part of Linux OS - outside kernel.

Am I being too picky or is there a real difference between native Linux "stuff" and drivers(s) build specifically for a device and not relying on the OS?

Modules are extensions of the kernel - once loaded they are kernel code.
Reduces the need to bloat the kernel for everyone, but allow those that need the functionality to get it simply.