Ranked: the 175 highest rated breathable hiking shoe models (2024) (page 9)
Breathable materials allow perspiration, evaporated by body heat, to escape. Fabrics come with different levels of breathability from low (0-5000) to high (15,000+) which should correlate to the level of exercise that is being done. For example, the level of breathability necessary for low-intensity exercise will be under 5000g/m2/24hr (grams of water vapour per square meter).