Hobnail

In footwear, a hobnail is a short nail with a thick head used to increase the durability of boot soles or provide traction.

The hobnails project below the sole and provide traction on soft or rocky terrain and snow, but they tend to slide on smooth, hard surfaces.

These boots tended to have large pointed hobnails on the extreme edges of the soles and heels to grip small roughness on steeply sloping rock and on snow, but have become less common with the invention of crampons.

Homemade hobnailed boots, which provide traction on ice and snow, can be created by driving roofing nails (with cut-off ends) through used rubber boots, which are then worn with normal shoes on the inside.

[2] A form of hobnailed boots were used by the British Royal Air Force for both ground staff and some aircrew, from the 1920s until just after the end of World War II.

A hobnail
A pair of hobnailed boots
Roman hobnails were shoe tacks , a type of clinching nail ; the narrowing tip was turned by a last held inside the sole as the nail was driven. So the tip did a U-turn back into the sole, clinching the nail in place.
Reconstruction of Ancient Roman caliga