THE PUB (Source – Wikipedia)
A pub, or public house, is an establishment licensed to sell alcoholic drinks, which traditionally include beer (such as ale) and cider. It is a social drinking establishment and a prominent part of British, Irish,  Breton, New Zealand, Canadian, South African and Australian cultures.
In many places, especially in villages, a pub is the focal point of the community. In his 17th-century diary Samuel Pepys described the pub as “the heart of England”.  Pubs can be traced back to Roman taverns, through the Anglo-Saxon alehouse to the development of the tied house system in the 19th century.
In 1393, King Richard II of England introduced legislation that pubs had to display a sign outdoors to make them easily visible for passing ale tasters, who would assess the quality of ale sold.  Most pubs focus on offering beers, ales and similar drinks. As well, pubs often sell wines, spirits, and soft drinks, meals and snacks.
The owner, tenant or manager (licensee) is known as the pub landlord or landlady, or publican. Referred to as their “local” by regulars, pubs are typically chosen for their proximity to home or work, the availability of a particular beer or ale or a good selection, good food, a social atmosphere, the presence of friends and acquaintances, and the availability of recreational activities such as a darts team, a skittles team, and a pool or snooker table. The pub quiz was established in the UK in the 1970s.

Specific Types of Pubs (Source – Wikipedia)
Gastropub
gastropub is a hybrid pub and restaurant, notable for serving good quality beer, wine and food.  The name is a portmanteau of gastronomy and public house, and was coined in 1991 when David Eyre and Mike Belben took over The Eagle pub in Clerkenwell, London.  The concept of a restaurant in a pub reinvigorated both pub culture and British dining, though has occasionally attracted criticism for potentially removing the character of traditional pubs.

Country Pub
A country pub, sometimes referred to as a tavern, is a rural public house. Traditionally, many functioned as a social centre for villages and rural communities, providing opportunities for country folk to meet and exchange news. Others, particularly those located on main thoroughfares, existed as coaching inns, providing accommodation or refreshment for travellers before the advent of motorised transport.In recent years many country pubs have either closed, or been converted to gastropubs, rather than continuing in their traditional role as a venue for members of the local community to meet and drink convivally.

Roadhouse
The term roadhouse was originally applied to a coaching inn, but with the advent of popular travel by motor car in the 1920s and 1930s in the United Kingdom, a new type of roadhouse emerged, often located on the newly constructed arterial roads and bypasses. They were large establishments offering meals and refreshment and accommodation to motorists and parties travelling by charabanc.

The largest roadhouses boasted facilities such as tennis courts and swimming pools. Their popularity ended with the outbreak of the Second World War when recreational road travel became impossible, and the advent of post-war drink driving legislation prevented their full recovery.  Many of these establishments are now operated as pub restaurants or fast food outlets.

Theme Pub
theme pub is a pub which aligns itself to a specific culture, style or activity; often with the intention of attracting a niche clientele. Many are decorated and furnished accordingly, with the theme sometimes dictating the style of food or drink on offer too. Examples of theme pubs include sports bars, rock pubs, biker pubs, Goth pubs, strip pubs, karaoke bars and Irish pubs.

Beer Houses
The 18th century saw a huge growth in the number of drinking establishments, primarily due to the introduction of gin. Brought to England by the Dutch after the Glorious Revolution of 1688, gin became very popular after the government created a market for “cuckoo grain” or “cuckoo malt” (grain that was unfit to be used in brewing and distilling) by allowing unlicensed gin and beer production while imposing a heavy duty on all imported spirits. As thousands of gin-shops sprang up all over England, brewers fought back by increasing the number of alehouses. By 1740 the production of gin had increased to six times that of beer and, because of its cheapness, it became popular with the poor, leading to the so-called Gin Craze. Over half of the 15,000 drinking establishments in London were gin shops.

The drunkenness and lawlessness created by gin was seen to lead to the ruination and degradation of the working classes. The different effects of beer and gin were illustrated by William Hogarth in his engravings Beer Street and Gin Lane.[14] The Gin Act 1736 imposed high taxes on retailers and led to riots in the streets. The prohibitive duty was gradually reduced and finally abolished in 1742. The Gin Act 1751, however, was more successful. It forced distillers to sell only to licensed retailers and brought gin shops under the jurisdiction of local magistrates.

By the early 19th century, encouraged by lower duties on gin, the gin houses or “Gin Palaces” had spread from London to most cities and towns in Britain, with most of the new establishments illegal and unlicensed. These bawdy, loud and unruly drinking dens so often described by Charles Dickens in his Sketches by Boz (published 1835–1836) increasingly came to be held as unbridled cesspits of immorality or crime and the source of much ill-health and alcoholism among the working classes.

Under a banner of “reducing public drunkenness” the Beer Act of 1830 introduced “beer houses”, a new lower tier of premises permitted to sell alcohol. At the time, beer was viewed as harmless, nutritious and even healthy. Young children were often given what was described as small beer, brewed to have a low alcohol content, as the local water was often unsafe. Even the evangelical church and temperance movements of the day viewed the drinking of beer very much as a secondary evil and a normal accompaniment to a meal. The freely available beer was thus intended to wean drinkers off the evils of gin, or so the thinking went.

Saloon or Lounge
By the end of the 18th century a new room in the pub was established: the saloon. Beer establishments had always provided entertainment of some sort—singing, gaming or sport. Balls Pond Road in Islington was named after an establishment run by a Mr. Ball that had a duck pond at the rear, where drinkers could, for a fee, go out and take a potshot at the ducks.  More common, however, was a card room or a billiard room.

The saloon was a room where, for an admission fee or a higher price of drinks, singing, dancing, drama, or comedy was performed and drinks would be served at the table. From this came the popular music hall form of entertainment—a show consisting of a variety of acts. A most famous London saloon was the Grecian Saloon in The Eagle, City Road, which is still famous because of a nursery rhyme: “Up and down the City Road / In and out The Eagle / That’s the way the money goes / Pop goes the weasel.”

A few pubs have stage performances such as serious drama, stand-up comedy, musical bands, cabaret or striptease; however, juke boxes, karaoke and other forms of pre-recorded music have otherwise replaced the musical tradition of a piano or guitar and singing.

The Public Bar
The public bar, or tap room, was where the working class were expected to congregate and drink. It had unfurnished floorboards, sometimes covered with sawdust to absorb the spitting and spillages (known as “spit and sawdust”), bare bench seats and stools. Drinks were generally lower quality beers and liquors.   Public bars were seen as exclusive areas for only men; strictly enforced social etiquettes barred women from entering public bars (some pubs did not lift this rule until the 1980s).

By the mid 20th century, the standard of the public bar had generally improved. Pub patrons only had to choose between economy and exclusivity (or youth and age: a jukebox or dartboard). By the 1970s, divisions between saloons and public bars were being phased out, usually by the removal of the dividing wall or partition. While the names of saloon and public bar may still be seen on the doors of pubs, the prices (and often the standard of furnishings and decoration) are the same throughout the premises.  Most present day pubs now comprise one large room, although with the advent of gastropubs, some establishments have returned to maintaining distinct rooms or areas.

Inns
Inns are buildings where travellers can seek lodging and, usually, food and drink. They are typically located in the country or along a highway. In Europe, they possibly first sprang up when the Romans built a system of roads two millennia ago.  Some inns in Europe are several centuries  old.

In addition to providing for the needs of travellers, inns traditionally acted as community gathering places.  In Europe, it is the provision of accommodation, if anything, that now distinguishes inns from taverns, alehouses and pubs. The latter tend to provide alcohol (and, in the UK, soft drinks and often food), but less commonly accommodation.

Inns tend to be older and grander establishments: historically they provided not only food and lodging, but also stabling and fodder for the traveller’s horse(s) and on some roads fresh horses for the mail coach. Famous London inns include The George, Southwark and The Tabard. There is, however, no longer a formal distinction between an inn and other kinds of establishment.

Many pubs use “Inn” in their name, either because they are long established former coaching inns, or to summon up a particular kind of image, or in many cases simply as a pun on the word “in”, as in “The Welcome Inn”, the name of many pubs in Scotland.

The original services of an inn are now also available at other establishments, such as hotels, lodges, and motels, which focus more on lodging customers than on other services, although they usually provide meals; pubs, which are primarily alcohol-serving establishments; and restaurants and taverns, which serve food and drink. In North America, the lodging aspect of the word “inn” lives on in hotel brand names like Holiday Inn, and in some state laws that refer to lodging operators as innkeepers.