What is the netting stuff knights wear with armour?

The netting that knights wear under their armor is called a "gambeson." It is a padded garment made of layers of fabric, often filled with material like wool or linen, which provides cushioning and protection against the impact of blows. The gambeson also helps to absorb sweat and improve comfort when wearing metal armor. Additionally, it serves as a barrier between the skin and the armor, reducing chafing and injury.