For better or for worse, JPEG photos are ubiquitous and you'll find them on every site on the web. There are other formats out there, GIF for example is having a big of a renaissance thanks to its animation capabilities.
Yet, it's popularity is dropping, it seems, as PNG is now the second most popular format on the web.
In fact, the number of GIF images on the web has been declining for years now with no end in sight. You might not think of it if you're on Tumblr, Reddit or even Twitter, but the popularity of animated GIFs alone can't stem the drop.
According to a study by W3Techs, PNG images are found on some 62.4 percent of all websites. Meanwhile, GIFs have dropped to 62.3 percent presence.
GIFs are still more popular on top 1,000 websites, it's got 67.9 percent penetration compared to 66.3 percent for PNG. But the trend is the same and PNG usage will overtake GIF in the next months.