Key vs Quay. Do you know the difference? #shorts

The video tutorial discusses the pronunciation and different meanings of the word 'key'. It highlights that 'key' can refer to a tool used for unlocking locks or solving problems, and also to a built structure, typically made of stone, used for mooring boats and handling goods.

Describe the structure referred to as a 'key' for boats.

What purpose does a 'key' serve for boats according to the text?