Internet phenomena are social and cultural phenomena specific to the Internet, such as Internet memes, which include popular catchphrases, images, viral videos, and jokes. When such fads and sensations occur online, they tend to grow rapidly and become more widespread because the instant communication facilitates word of mouth transmission.

This list focuses on the Internet phenomena which are accessible regardless of local internet regulations.

Challenges generally feature Internet users recording themselves performing certain actions, and then distributing the resulting video through social media sites, often inspiring or daring other users to repeat the challenge.