Why do some stars have spikes and points?

Stars do not have spikes or points. This happens because of optical defects and diffraction in the particular optical instrument you are using to see the star, such as your eye, or the lens of a camera. Reflecting telescopes hang a secondary mirror from a 4-segment 'spider' at the front of the tube, and this causes diffraction spikes in all the stars seen through the telescope because of optical diffraction. Refractors do not have this problem because there is no secondary mirror or other obstruction in the light path. The human eye is also a lens system under muscular tension by the eye muscles, and this causes various kinds of distortions in the shapes of unresolved objects. If you do not have 20/20 vision, looking at stars at night makes them look like luminous spotted snowballs!