A substance in which the domains are all aligned in the same direction is called a ferromagnet.

Here's a breakdown:

* Domains: In a ferromagnetic material, the atoms have their magnetic moments (think of tiny magnets) aligned in small regions called domains.

* Alignment: In a ferromagnet, these domains are spontaneously aligned in the same direction, creating a strong overall magnetic field.

Examples of ferromagnetic materials include:

* Iron

* Nickel

* Cobalt

* Some alloys

Let me know if you'd like to explore other types of magnetism like paramagnetism, diamagnetism, or antiferromagnetism!