Choose waterproof, breathable and flexible. If you do not go to high mountains , take a low model (or mid-high if you need an ankle support). Always take one or two sizes above your usual size.
Especially no cotton, which is a real blotter! In winter, a 70% merino sock is preferred . In summer, you can opt for a mixture of elastane and silk. If we walk intensively, we can afford a more “technical” pair that will prevent blisters (Monnet or Socks of France, about 30 €).
Indispensable in mountains, Nordic walking and hiking beyond 60 years. They allow to better distribute the effort on the four limbs and to work well the cardio-vascular system .
As a bonus
For long walks (from half a day), it is better to wear clothes made of breathable fabric (rather than cotton ) that wicks away perspiration and dries easily. Also think about the polar (for the evening) and the rain jacket depending on the climate.