Georgia State University
Georgia State University: Hyper Physics: Ferromagnetism
This site from the Georgia State University provides a good overview of ferromagnetic materials, introducing concepts such as magnetic domains, hysteresis, the curie temperature, and magnetostriction.
Georgia State University
Georgia State University: Hyper Physics: Magnetic Domains
A great introduction to magnetic domains, including pictures which illustrate the effect on domains caused by external applied magnetic fields.
Wikimedia
Wikipedia: Magnet
Wikipedia.com provides an excellent introductory site on magnets. Including basic information describing different types of magnets and their characteristics.
National High Magnetic Field Laboratory
Magnet Academy: Magnetic Domains
In ferromagnetic materials, smaller groups of atoms band together into areas called domains, in which all the electrons have the same magnetic orientation. That's why you can magnetize them. See how it works in this Java tutorial.
Other
All About Circuits: Magnetism and Electromagnetism: Permanent Magnets
A good explanation of what the property of magnetism is and how it occurs naturally in lodestone and can be generated in metals such as steel. It describes how a ferromagnetic material such as iron becomes magnetized when near a...
National High Magnetic Field Laboratory
Magnet Academy: Diamagnetism and Paramagnetism
Think iron, nickel and other "ferromagnetic" substances are the only ones with magnetic properties? In fact, everything reacts to magnetic fields in some way.
Lumen Learning
Lumen: Boundless: Magnetism and Magnetic Fields: Permanent Magnets
This short module covers permanent magnets, the concept of polarity, and the manufacture of permanent magnets. Includes some quiz questions.
Georgia State University
Georgia State University: Hyper Physics: The Curie Temperature
A brief definition of the Curie temperature for ferromagnetic materials.
Wikimedia
Wikipedia: Ferromagnetism
This site from Wikipedia provides a wonderful in-depth explanation of ferromagnetism, covering the atomic behavior which is responsible for ferromagnetic properties. Also introduces the concepts of magnetic domains and the Curie...
Other
Ndt Resource Center: Magnetic Domains
This site is an introduction to magnetic domains, including a picture showing distinct domains taken through a process called "Magnetic force microscopy."
Tech Target
Whatis.com: Permeability
This resource defines magnetic permeability and then describes how it is used to classify materials as diamagnetic, paramagnetic, or ferromagnetic.