Toasters have evolved significantly since bread was first toasted over open fires. Early electric toasters in the 1900s had basic heating elements but issues with burning. The 1905 invention of nichrome wire allowed toasters to heat surfaces above 154°C without damage. The 1909 toaster by General Electric was the first commercially successful electric toaster. Later innovations included the 1913 "automatic toaster" that could flip bread without touching it and the 1919 pop-up toaster with a variable timer to prevent burning. The invention of sliced bread in the late 1920s increased toaster usage as it was now easier to toast individual slices.