Vulkan Instance gathers per application state and allows us to create a logical device on which almost all operations are performed. Before we can create an Instance object, we should think about the instance-level extensions we want to enable. An example of one of the most important instance-level extensions are swapchain related extensions, which are used to display images on screen.
Extensions in Vulkan, as opposed to OpenGL, are enabled explicitly. We can't create a Vulkan Instance and request extensions that are not supported, because the Instance creation operation will fail. That's why we need to check which extensions are supported on a given hardware platform.