Silly question - What are the extra holes for?

[somnif]

So, I just finished populating a Pork Barrel board, and for one component, I was annoyed to find the hole spacing didnt fit my piece (C21, ceramic cap). I then noticed there was a small hole with a silk screened-over solder pad that WAS in the proper spacing. I checked the build doc and discovered that it was in continuity, so brilliant, in it went.

But this made me curious. What are all the other small, silk screened over holes for? Looking at the board a lot of them have traces to and from them, but I cant tell what purpose they have. Are they to connect the front of the board to the back? Are they for mods? Inquiring over-caffeinated minds want to know!

[Haberdasher]

Those are called vias.  In a nutshell, they allow a trace to hop to the other side of the pcb and continue on its way.

[neandrewthal]

Or in other words...

Are they to connect the front of the board to the back?

Yes!

[somnif]

Cheers mates, nice to know I'm still coherent enough to form a valid theory. Thanks!