tl;dr: Medium uses a technique called progressive image loading to improve the performance and user experience of its website. This involves loading low-resolution versions of images first, and then gradually replacing them with higher-resolution versions as they become available. This allows users to see images on the page more quickly, without having to wait for all of the high-resolution versio
![How Medium does progressive image loading](https://cdn-ak-scissors.b.st-hatena.com/image/square/dfb065053ddec7d3fc2f24f60ad4996026e8d563/height=288;version=1;width=512/https%3A%2F%2Fjmperezperez.com%2Fstatic%2Fimages%2Fposts%2Fmedium-placeholder.png)