Do you guys know your router bits?

Do you know how to tell a plunge bit from a non-plunge bit?

A non plunge bit has cutters around the periphery, but not the center. It can enter grooves from the side and cut moving sideways.

A plunge bit has cutters that go all the way to the center of the bit face. It can cut moving vertically as well as sideways.
Above see the bar across the center as well as the two edge cutters? Without this bar, when you drive the bit straight down the dead spot in the middle will prevent plunging (just burns) unless you crush the wood. Can't use a non plunge bit on a plunge router to enter a hole vertically... like you would for a lettering template bit or a stopped groove where you have to drop the bit in vertically and then move it sideways. It has to cut its way in on the plunge, then cut on the side when you move it.

Here is another pictorial anatomy of a plunge bit

Note that the following round nose bits are plungeable because the cutters go all the way to the center.