High Street is a common street name for the primary business street of a city, town, or village, especially in the United Kingdom and Commonwealth. It implies that it is the focal point for business, especially shopping. It is also a metonym for the retail sector. While many streets, such as Camden High Street (in London), bear this name, streets with similar function but different names are often referred to as "high street".

With the rapid increase in consumer expenditure, the number of High Streets in England grew from the 17th century and reached a peak in Victorian Britain, where, drawn to growing towns and cities spurred on by the Industrial Revolution, the rate of urbanisation was unprecedented. Since the latter half of the 20th century, the prosperity of High Streets has been in decline due to the growth of out-of-town shopping centres, and, since the early 21st century, the growth of online retailing, forcing many shop closures and prompting the UK government to consider initiatives to reinvigorate and preserve the High Street.

High Street is the most common street name in the UK, which according to a 2009 statistical compilation has 5,410 High Streets, 3,811 Station Roads and 2,702 Main Streets.

In Middle English the word "high" denoted superior rank ("high sheriff", "Lord High Chancellor", "high society"). "High" also applied to roads as they improved: "highway" was a new term taken up by the church and their vestries during the 17th century as a term for all public roads between settlements. From the 19th century, which saw a proliferation in the number of public roads, the term "highway" lost its specific meaning, and was legally defined as any public road (e.g., the Highway Code regulates UK public roads). The term "high street" assumed a different meaning, that of a street where the most important shops and businesses were located.

In Britain, the term 'high street' has both a generic and a specific meaning: people refer to 'shopping on the high street' both when they mean the main retail area, as well as the specific street of that name. Many former British colonies, including Canada, Australia, New Zealand, and the US region known as New England (especially Massachusetts), adopted the term to refer to retail shopping areas. In other parts of the Northeastern United States, the town's main retail street may still be a street named High Street (such as in Columbus, Ohio), but the term is seldom used to refer more generally to a retail street or district. Main street is used in the island of Ireland.

In Britain, some 3,000 streets called High Street and about 2,300 streets with variations on the name (such as Upper High Street, High Street West) have been identified, giving a grand total of approximately 5,300. Of these, more than 600 High Streets are located in London's boroughs.

Main Street is a term used in smaller towns and villages in Scotland, while in North East England Front Street is common. In Cornwall, some places in Devon and some places in the North of England, the equivalent is Fore Street; in some parts of the UK Market Street is also used, although sometimes this may be a different area where street markets are currently (or were historically) held.

Following the Great Fire of London (1666), the city of London was completely rebuilt. New planning laws, governing rebuilding, designated four types of street based on the size of their carriageways and the types of buildings. Shops were permitted in the principal street or 'high street', but not in the by-lanes or back streets. This may have been based on the need for high visibility in order to regulate retail trade, as well as to avoid congestion in the narrow lanes and back streets. Accordingly, from the 17th century, the term "High Street" gradually assumed a narrower meaning and came to describe thoroughfares with significant retail in large villages and towns.