A Nether Portal is a structure in the game Minecraft that allows players to travel between the Overworld and the Nether, a dangerous alternate dimension. To create a Nether Portal, players must build a rectangular frame using obsidian blocks and activate it with flint and steel. The portal emits a purple, swirling energy, indicating that it is ready for use. When players step into the portal, they are instantly transported to a corresponding location in the Nether. This dimension features unique resources, hostile mobs, and various biomes, making it essential for exploration and crafting in the game.