The Dwemer were an ancient elder race, closely related to Elves and Orcs, in Tamriel. Their disappearance was caused by their king during the Battle of Red Mountain using his 3 tools on the Heart of Lorkhan. They have left behind a massive legacy of technology and lore that fascinates tinkerers, blacksmiths and wizards to this day.
Also known as dwarves, they were masters of magic and of armor and weaponry. Dwemer armor and weapons are still manufactured by skilled blacksmiths across Tamriel, especially Skyrim, and fill all the same niches as other styles.
Dwemer ruins litter the landscapes of several of Tamriel's realms, including Hammerfell (near Stros M'kai) and Skyrim. If one delves deeply enough, they will find that Dwemer places and technologies have been appropriated by the Falmer, their ancient enemies.
Many Dwemer weapons and automatons are still functional in these deep dungeons, and seem to be powered by soul gems. They use a variety of weapons, from blunt metal to electricity to scalding steam. One city in Skyrim is in fact a resurrected Dwemer ruin: Markarth, formerly the capitol of the Reachmen.