What is a Kernel

 We can start definying this concept with this simple image

What is?

Kernel is the bridge between the hardware and software located in the core of a computer system, it has full control of everything in the system and the responsible for preventing any conflict between diferent processes (optimizing the availbale resources - multitasking), in simple words it is in charge of interpreting the outpouts sent by your     devices like the CPU, Memory and Devices as keyboards, mouse, etc 

In the case of the image with a basic software, I am sure have you ever used this program to create documents, files, academic articles or something as simple as copy and paste photos to print them, yeah this is called "Microsoft Word" (with my first blog URL), in this case the outpouts sent by your keyboard when your type or the clicks when you select any option in the menu are interpreted, processed and sent to the software by the kernel