What is the High Street?

You will hear this term often in the UK but not in the US or other countries.

So what exactly is the High Street?

From Wikipedia:

High Street, or the High Street (often abbreviated to High St), is the generic name (and frequently the official name) of the primary business street of towns or cities in the United Kingdom and Ireland. It is usually a focal point for shops and retailers in the city centre, and is most often used in reference to retailing. The equivalent in the United States and Canada is Main Street...