When it comes to identifying spectacular innovations that have changed the world for women, there are quite a lot of candidates. Getting rid of the corset? A+++. The realization that "hysteria" is actually nonsense and that women don't have "weak nerves"? Well done and well overdue. But when discussing which actual, physical inventions most changed the world for women — as many people are doing in April, as we celebrate National Inventors Month — it can be a tricky to figure out what mattered most, and what really gave women the most benefit as a social group. The printing press, for instance, changed the world entirely, but it didn't target women on their own, so it's out. Inventions that changed the world for women, specifically, have to meet a few conditions: they have to materially shift the ways in which women have been constrained or damaged by gender inequality; they have to be safe; and they have to make a significant and measurable difference to women, specifically.
Some of the inventions that have made this list weren't created to help women, or indeed to become widely known at all, while others were specifically intended to better the condition of women across the board. But intention doesn't actually have too much impact on whether they improved women's lives vastly.
And that improvement becomes starkly obvious when you compare places where these inventions are available to places where they aren't, and the conditions of women in both. When ingenuity creates a more equal world, it's a brilliant thing.