Modern menswear is built around the suit and its variations. The lounge suit began in nineteenth-century Britain as sportswear and country clothing, and in the early twentieth century a plain one-coloured suit replaced the black frock coat as daywear.
Bespoke
A tailor cuts a pattern from your own measurements, giving the best fit and free choice of cloth. On Savile Row, tailors argue the term means a suit cut and made by hand. The Savile Row Bespoke Association was founded in 2004, and its members typically put at least 50 hours of hand labour into a two-piece suit.
Made to measure
An existing pattern is adjusted to fit you, with a limited choice of options and fabrics.
Ready-to-wear
Sold ready-made. Since the 1960s most suits have been mass produced this way, and a tailor can make small alterations.
Savile Row
Tailors arrived in the area in the late eighteenth century, first on Cork Street around 1790 and on Savile Row itself by 1803.
Sources: Wikipedia: Suit and Wikipedia: Savile Row.