What is the origin of the idiom "the best thing since sliced bread" and when to use it?

The origin of the idiom "the best thing since sliced bread" is traced back to the early 20th century, specifically to the 1920s in the United States. It refers to something or someone that is regarded as a remarkable or revolutionary development, invention, or innovation. The idiom gained popularity after the widespread introduction of sliced bread, which was considered a significant advancement in convenience and ease of use. Since then, the phrase has been used to express high praise and enthusiasm for a new product, idea, or concept, suggesting that it is the most significant or impressive thing to come along in a long time.