Worked example: A neodymium magnet has coercivity H_c ≈ 10⁶ A/m and remanence B_r ≈ 1.2 T. Estimate the maximum energy product (a figure of merit) and compare with a fridge magnet (B_r ≈ 0.1 T, H_c ≈ 10⁴ A/m). Step 1: (BH)_max ≈ B_r·H_c/4 (order of magnitude for a square loop). Step 2: Neodymium: 1.2 × 10⁶/4 = 3×10⁵ J/m³ = 300 kJ/m³. Step 3: Fridge magnet: 0.1 × 10⁴/4 = 250 J/m³ — over 1000× smaller! Step 4: Meaning: a tiny neodymium cube stores as much magnetic energy as a large ferrite block — why earbuds and EV motors use them despite the cost. Step 5: Domain view: huge H_c means domain walls are strongly pinned by the Nd₂Fe₁₄B microstructure — reversing needs an enormous field. Conclusion: the hysteresis loop's area and squareness, set by domain-wall pinning, decide whether a magnet is 'hard' or 'soft'.