What are ores, you say, right? Well, I'll tell you what ores are now...
Ores are collected for crafting, decorating and for other purposes, such as for tools and armour. Ore can also be combined to create a block of the material's type.
Coal - Used for furnaces, sometimes found on cliffs but also underground
Iron - Used for weaponry, armoury, decorating etc. Found underground.
Lapis Lazuli - Only used basically for dying wool. Found underground.
Gold - Same uses as Iron, and when crafted into a weapon, tool or armour, easiest to enchant. Found underground.
Redstone - Used for advanced stuff e.g. piston door, and crafting pistons etc. Found underground.
Diamond - Same uses as Iron, best ore used for weapons, tools etc. Found underground.
Emerald - Rarest of ores in the Overworld, only used for decorating, crafting etc. Found underground.
Nether Quartz - Only found in the Nether, used for decorating, crafting etc.
Maybe this is enough information about ores!