Sometimes presented as "the best thing since sliced bread," "the greatest thing since sliced bread" is an idiomatic expression that gained popularity during the first half of the 20th century and has remained in use in the years since. Typically, this idiom is used to express a sense that something is innovative, outstanding, and generally superior to something that has come before. A wide range of situations may trigger use of this particular English saying, ranging from the creation of an idea to the invention of some new product.
The origin of the idiom has to do with the offering of baked loaves of packaged bread from various retail outlets beginning during the 1920s. At that time, emerging supermarket chains began to offer loaves of bread that were mass produced and pre-sliced before reaching the market. This was a great innovation for the time, since most consumers purchased bread that required slicing at home, although some bakeries would slice loaves for customers once the purchase was complete. Since the slicing was automated, the thickness of each slice was more or less the same, a feature that delighted many customers and greatly increased the popularity of store-bought bread.
By the 1940s, referring to something as "the greatest thing since sliced bread" had become a relatively common expression in many parts of the world. Advances in technology and the creation of consumer products such as television sets, automatic dishwashers and an expanded range of features on the automobiles of the day were all seen as wonderful innovations. In an age when new and improved goods and services were announced regularly, the occasion to use this idiom was common, and it was often used both in word of mouth recommendations between consumers and in various types of media advertising.
Over time, this phrase moved beyond new products and was applied to other scenarios. Young lovers might say that the objects of their affection possessed this exalted status, or a supervisor or manager could give type of praise of this type to an idea developed by an employee that saves time and money for the company. Today, referring to something as being the best thing since sliced bread is still used in some circles, although the majority of consumers today cannot remember a time when pre-packaged loaves of bread were not sliced.