What is pilling and how to prevent it?
Wool pilling happens when the fibres are broken through chafing, washing and generally just wear. The broken ends of the fibres intertwine and form knots, which appear commonly to the sides of sweaters, cuffs and inner arms. It can also happen to 100 % synthetics, the key here is broken fibres, natural or not.
High-quality clothes have longer and stronger fibres, which makes them less prone to pilling. Also, if your wool fabric is sleek like on a suit (worsted to align and bind the fibres), pilling will take a longer time - but could still happen. Blends are more susceptible to pilling compared to 100 % wool: even when polyamide or polyester makes the fabric more durable overall, the wool fibres break as easily as before.
To avoid pilling in the first place, choose clothes with high-quality materials, wash them with the appropriate program (not too hot, don't spin hard, not in a completely full machine etc.) and avoid rubbing them, if possible.