In Minecraft, Ingots are simple units of metal, very commonly used in crafting. Vanilla Minecraft and Thermal Foundation add Ingot types for all of their metals and alloys.
Ingots come in three varieties as of 1.16: iron, gold, and netherite. Two of them can be made by smelting iron ore or gold ore in a furnace. Ingots of all sorts can be used to make armor, tools, and various other items and blocks. Ores were originally only able to be smelted by being thrown into a fire on the ground. However, ever since furnaces were added to Minecraft, there is now an easier way to smelt ore.
For the complete list and how to craft ingots, view the following.
List of all ores and their uses in Minecraft
How to craft a Netherite Ingot in Minecraft