Snowdin

is the town encountered by the Player in the Underground after they leave the Ruins. The town has many guardsmen in it, including Sans and Papyrus, presumably because it is close to the entrance from Mt. Ebott, so is most likely to have humans coming through. Departure from the town takes the Human to Waterfall by foot, or by way of the River Boatsman to either Waterfall or the Hotlands.

Description
Despite being subterranean, Snowdin is somehow covered in a perpetual layer of ice and snow (thus the name) and because of how cold it is, it's mainly home to monsters with thick fur, such as bears and bunnies. The town also houses the two skeleton sentries (Sans and Papyrus) and the canine members of the Royal Guard (Doggo, Greater Dog, Dogamy and Dogaressa). Rebellious teenage Snowdrakes live on the outskirts along with Icecaps. Another monster in the outskirts inadvertently caused a local tradition that is similar to the human festival known as Christmas, where monsters place presents under decorated trees. Snowdin's buildings include a SHOP, an INN (owned by two rabbit sisters), Papyrus and Sans's house, a Library with a misspelled sign, and Grillby's bar.

Main Story
After confronting Toriel and leaving the Ruins, the character meets Sans and Papyrus in the Snowdin Woods prior to town, where Sans engages in rhetoric with the protagonist, and Papyrus attempts to confront the player with several puzzles. After making it through these puzzles and the Royals Dogs, the hero makes it into the town, where they pass through and ultimately confront Papyrus in battle. If defeated by Papyrus, they are placed into an easily escaped literal "Doghouse." After Papyrus is defeated (via death, mercy, or losing to him too many times, after which he will give you the choice to battle him or not), the player makes there way towards Waterfall, where along the way they are attacked repeatedly by Undyne, the Captain of the Royal Guard.