What is a B-H curve (magnetic flux density-magnetic field curve)?

The B-H curve is a graphical representation of the relationship between the magnetic flux density (B) and the magnetic field strength (H) required to demagnetize a given magnet. This graph is the second quadrant of a four quadrant hysteresis curve.
The magnetic flux density increases in proportion to the field strength until it reaches a saturation point and becomes constant as the field strength increases.
Magnetic flux density is measured in Gauss (G) or Tesla T, where 10,000 Gauss is equal to 1 Tesla. Magnetic field strength is measured in Oersteds (Oe). When analyzing anisotropic materials, if the magnetic field is not applied parallel or perpendicular to the object anisotropy axis, the B-H curve measurements are not valid.