In a nutshell, when a video "goes viral," it means that a video has become so popular that it now spreads exponentially across the Internet and multiple social media platforms like Facebook, Instagram, TikTok, and YouTube.
When something goes viral you don't have to post and share the video repeatedly to ensure it gets an increasing number of views. Instead, people voluntarily share the video content or social media algorithms automatically put the content on the screens of users.
Think of going viral as reaching a threshold of growth. A point beyond which the video’s popularity and view count grows faster than you can control. For most marketing purposes, going viral is a good thing. It means that a given advertisement or piece of video content is going to be seen by many more people than initially projected.