What is "Sealing the corner posts"?

[Sarvoth]

I keep coming across people mentioning "Sealing gates" or corner posts and I'm not sure what that means specifically or why it's being said.
I apologize if this comes off as an ignorant to some of you, I started playing just this morning.

Thanks in advance for any replies.

[JellyBean]

From what I've been told, sealing a corner post makes
it so you cannot build anymore walls off of it. I suppose
It's to stop some random stranger from building a wall
out of nowhere just to hinder you.

[Danno]

Indeed, sealing a cornerpost makes it so you can't build from it anymore. It's particularly important you seal the cornerposts at your gate so that someone doesn't simply extend it from your gate, go in front of your gate, and connect to the other cornerpost, effectively trapping you within your own home.

I'm not sure if you become unable to create a gate if you seal the cornerposts first since I've never tried it before... so build your gate before sealing them to be safe.

You don't have to worry about this with roundpole fences since they're laughable at best and don't have a sealing option. To seal a palisade cornerpost, right-click the cornerpost and choose the "Seal" option. I assume it's the same for brickwalls, though I can't say that from experience.

[Oddity]

You can still build a gate as long as one of the cornerposts is unsealed.