The glass cocktail shaker is the oldest type of cocktail shaker and the professional's favourite. Its true name is the Boston Shaker and its key virtue is its shear simplicity. It has just two parts - the metal shaker tin, usually 28 oz, and the mixing glass, 16 oz. The rim of the glass fits inside the rim of the tin. The ingredients go in, the two parts go together - and shake, as simple as that! Alternatively, you can just use the mixer glass if you prefer your drink stirred rather than shaken.

Of course, it isn't as easy as that. It's the skill of the bartender that makes it look that way. The other great skill of the bartender is knowing what to put inside the Boston glass cocktail shaker to make your perfect drink. Not only are there so many cocktails to choose from, each one probably has as many variations as there are bars to drink them in.

Some cocktails remain firm favourites. Drinks International asked 100 of the world's best bars to rank their best-selling classics, and these were the top four.

The Old Fashioned

Ever since watching Don Draper in Mad Men, we've fallen back in love with the old fashioned cocktails. The first recorded use of the name Old Fashioned was in 1886, so it was clearly a classic even then. Today, no fewer than a quarter of the bars polled by Drinks International rated it their number one. As you would imagine, there is debate of course, about the best type of mix to use, and whether to add water and fruit, but the usual components are: 1½oz bourbon or rye whiskey, 2 dashes of Angostura bitters, 1 sugar cube and a few dashes of plain water. Garnish with a twist of orange peel and a cocktail cherry.

The Negroni

The Negroni is a stronger, punchier variation of the Americano, supposedly invented by Count Negroni in Florence in 1919. The world's favourite gin cocktail - equal parts gin, Campari and sweet vermouth, with ice and an orange slice to garnish. Most experts agree it should be stirred rather than shaken.

The Manhattan

This cocktail came from the Manhattan Club in the late 19th century. In terms of authenticity, that is important: the club was famous then for its excellent rye whiskey, so rye whiskey is probably the original basis of the cocktail. That said, if you prefer bourbon, who cares about authenticity? The proportions should be 2 parts rye whiskey or bourbon to 1 part red vermouth, with a dash of orange bitters, with ice.

The Daiquiri

The classic Daiquiri is not the thick strawberry or banana cocktail, beloved of those who don't like drinking, but a refreshing, zingy cocktail of Cuban heritage. Mix the juice of half a lime with a teaspoon of sugar, then add 2 oz of good white rum and shake well with ice. Strain and serve with a wedge of lime.

Finally, never forget the words of the great cocktail expert David A Embury - 'A cocktail will never be better than its cheapest ingredient.'