The predecessors of the Safety Razor were called straight razors that evolved from the initial ones in the Bronze Age.
The safety razor were invented by King C. Gillette.
The first safety razor was a double-edged safety razor with replaceable blades.
Gillette's marketing idea was to sell razors at a loss, but the replacement blades were at a higher margin and provided continuous sales.
His advertising campaigns and slogans highlighting the ineffectiveness and lack of safety of the straight razor.
Safety razors' blades were extremely hard to sharpen, and were meant to be thrown away after one use.
They also cost more over time.
Around 1960, stainless steel blades which could be used more than once became available, reducing the cost of safety-razor shaving.
The first such blades were made by the Wilkinson firm, famous maker of ceremonial swords, in Sheffield.
Gillette, Schick, and other manufacturers soon followed suit and started manufacturing stainless-steel blades.
From there on, multiple-blade cartridges and disposable razors followed.
