I always like to define a star topology as a network where all devices connect to a central point. I have seen numerous materials that refer to a central hub, and while this is correct terminology, I find some people get fixated on the word hub. That central point could be a hub device, it could be a switch, it could be a router, or it could be a server. Most likely, it will be a switch. You might be puzzled at my inclusion of a server in that list. While it is unusual, it can be done given the right hardware and software. I have also found that some materials draw a star topology with a device that looks like a server in the middle, and that becomes a fixation too.
In Figure 5.5, I have placed a switch as the central device, as this is the most common implementation:
Quite often you will see star topologies illustrated the way I have done...