The fibres that we use for making fabrics are short and weak. They cannot be made into a strong, flexible fabric if they are just pushed together. The fibres have to be made into yarn before they can be used.

Yarn is made by a process called spinning. In this process the fibres are twisted and stretched together. The twisting of the fibres makes them grip each other strongly. The stretching pulls them into a long thread.

A yarn may be made from all the same kinds of fibres. For example woollen or cotton yarn is just made from wool or cotton fibres. Some yarns can be made from a mixture of fibres. For example some artificial fibres, such as polyester, may be mixed with cotton. This gives a yarn which has properties that are different from a yarn made only from either fibre.

Yarn is strong. It can be woven or knitted together to make fabrics without breaking. If you look at the threads in your clothes you are looking at the yarn from which they are made.