The term "merino" was originally restricted to denote the wool of merino sheep reared in Spain, which can be traced back as far as the 12th century. Today in the knitting trades, "merino" generally implies an article made from the very softest wool.

Merino sheep are found all around the world but typically dominate in Argentina, Australia, New Zealand, South Africa and the western United States where sheep are bred for their wool rather than their meat.

Merino Wool is one of the most used natural fibres (this fibre can stretch to 50% its length without breaking), length (from 35 to 350 mm) and is also suitable for felting. These characteristics are due to the fibre's external surface, which is made up of numerous very small scales.