In China, there is no TikTok. There is only Douyin.

After President Biden signed a bill on Wednesday forcing Chinese company ByteDance to sell its ownership of TikTok, the United States moved one step closer to an internet without the short video app. The legislation opened the door to a possible ban of the social media platform if TikTok fails to find a U.S. government-approved buyer within a year.

Douyin is also owned by ByteDance. It is a staple of the Chinese internet the way TikTok is in the rest of the world. But because it has no presence outside China, Douyin, which means a “shaking sound” in Chinese, is not as well known globally.

But Douyin is critical to ByteDance’s finances. Its continued success will be a significant factor in how the parent company assesses what it plans to do with TikTok. Will ByteDance succumb to political demands from Washington, or will it refuse to sell TikTok and face the consequences?

Here is an overview of Douyin.

Douyin is the most popular short-video app in China, and it is one of the most visited social media platforms in the country. As on TikTok, the videos on Douyin appear in a vertical format and users swipe up to get to the next offering. There are other similarities to TikTok. The Douyin algorithm learns your interests from how you interact with the videos you are shown and feeds you an endless stream of content.

Douyin debuted in September 2016 in China, a year before ByteDance introduced TikTok for overseas markets. Initially, Douyin focused on China’s big cities where young smartphone users were early adopters of new social media. Douyin reached more than 700 million active monthly users in May, meaning it was being used by a majority of China’s internet users, according to QuestMobile, a Chinese data firm.